When Biz Stone and Evan Sharp—two founders who literally built the platforms that defined the last 15 years of social media—bet $29 million on an alternative model, something fundamental is shifting. Their new company West Co just launched Tangle, an invite-only app asking users a single question: "What's your intention for today?" This isn't a feature tweak. It's a declaration that the 15-year bet on engagement maximization—the model that made their previous companies billions—has entered its deflation phase. And credible founders with institutional backing now see opportunity in the alternative.

The genius of engagement-maximized social was simple. More time on platform equals more advertising revenue. More outrage and dopamine hits equals more time. More data equals better targeting. The formula worked perfectly for 15 years. It also, as Evan Sharp put it to the Financial Times, created "the terrible devastation of the human mind and heart that we've wrought."

Now the people who built those systems are walking away from the model. That matters.

Stone and Sharp aren't critics shouting from outside the tech industry. Stone helped build Twitter from its inception. Sharp built Pinterest into one of the few platforms that actually monetized without pure engagement addiction. They understand the architecture, the incentives, the technical challenges. They've both made tens of millions from the engagement model. And they're betting that model's dominance is ending.

Tangle, their first product, starts absurdly simple. Open the app. It asks: "What's your intention for today?" You share goals with friends. You capture what actually happened. You see patterns. That's it. No algorithmic feed. No infinite scroll. No attention extraction machinery.

The $29 million seed round, led by Spark Capital, signals something bigger than a single product. Spark Capital doesn't fund moonshots without category conviction. They're betting that the market for intention-based social isn't a niche—it's the next phase of the category. Remember when Facebook launched "meaningful interactions" features in 2017 and everyone laughed? The company was too dependent on engagement-maximization revenue to commit. But alternative platforms don't have that lock-in. They can actually build what they claim.

The timing here is crucial. We're 15 years into social media's dominance. That's roughly the same lifespan platforms got in previous eras before alternatives emerged. MTV owned music television for roughly 15 years before YouTube disrupted it. Google held search dominance for about 12 years before mobile fragmentation began. Social's 15-year run is hitting that inflection point where the original winners become the obvious targets for disruption.

But there's a timing gap here. Tangle is still invite-only. The company is still figuring out the product. Stone told the FT the app could "change significantly" before public launch. That's founder-speak for: we built this to make a point about what social could be, but we don't yet know if users want it enough to sustain a business. That's the actual question. Intention-based design sounds great in manifesto form. Sustaining it at scale, against platforms designed to extract every minute of human attention, is a different challenge.

The market conditions are better than they were six months ago. TikTok's regulatory chaos has made creators nervous. The Bluesky exodus from Twitter proved users will leave for different incentives. Gen Z is actively choosing platforms based on authenticity rather than reach—BeReal's early success validated that signal. The window isn't just open. It's actively widening.

For builders, the signal is clear: If you're thinking about building a social platform, founders with real credibility now have permission to fail differently than you. Evan Sharp built Pinterest into a $25 billion company. He knows the playbook. If he's willing to bet $29 million against engagement maximization, the category ceiling is higher than most builders think.

For investors, this is pattern recognition. Every major category shift eventually has a moment where a credible insider bets against their own previous success. Jeff Bezos betting on cloud computing while Amazon retail ruled looked insane until it didn't. Satya Nadella betting Microsoft's future on Azure and AI while Windows still printed money. This has that flavor. The insiders see the structural shift coming. They're positioning accordingly.

For enterprises, this is a different kind of signal. If alternative social platforms gain traction, employee communication strategies change. If Tangle proves users will actually engage authentically without algorithmic manipulation, that becomes a case study for internal tools, external customer engagement, community building. Slack's dominance happened because it offered superior communication design over email—not because everyone suddenly hated email, but because better design proved people would switch. Intention-based social could follow that pattern.

The next 18 months are critical. Tangle needs to prove three things: First, that users will actually show up if engagement isn't being maximized. Second, that the business model works (and it's not clear what that is yet—no ads mentioned, no subscription details). Third, that the core insight about intention-driven social isn't just correct for founders and investors, but correct for regular people making regular decisions about where to spend time.

That last one is the hardest. The engagement-maximization model didn't dominate by accident. It dominated because it works. Because humans find algorithmic feeds more compelling than intentional ones. Because outrage is more engaging than goals. Tangle is betting that something fundamental has shifted in how people feel about that trade-off. It's a big bet. But it's a bet backed by people who know exactly what they're betting against.

When founder-backed capital flows into alternatives to a dominant model, the dominance itself is being questioned by people who understand it best. Biz Stone and Evan Sharp's $29 million bet on intention-based social isn't just a startup announcement—it's insider validation that engagement-maximization's era of unopposed dominance is ending. Builders should watch this closely: if Tangle reaches meaningful scale, alternative social becomes a viable category. Investors should note: the moment when insiders bet against their own playbook is usually when the next wave begins. Enterprises should prepare: employee and customer communication strategies may need to shift if authentic, intention-driven platforms prove sustainable. The critical threshold is adoption metrics by mid-2026. If Tangle reaches 100K active users, the pattern becomes undeniable. If it stalls, the critique remains powerful but the business case unproven. Either way, the inflection point is worth monitoring closely.