If you start from successful startups, you find they often behaved like nonprofits. And if you start from ideas for nonprofits, you find they’d often make good startups.
It’s a risky and disingenuous proposition to build a website and community on one model — the “Good” and charitable model — and then bait-and-switch the userbase once the founder’s numbers get drawn. It’s a scummy behavior to engage in, much less evangelize.