I haven't heard a rationale for equity crowdfunding that makes sense to me. It sounds straightforwardly dangerous. The whole thesis for startup investing is that investors build large portfolios where the winners pay for the losers. A 2x return is a out-of-the-park home run for a retail investment in a public company, but is, mathematically, a failure for a startup investor, because only 1-2 companies in a portfolio of 10 will succeed.
That, and a few other arguments, here as well: https://news.ycombinator.com/item?id=10481136