That's interesting, but it sounds too simple. Surely any of the competitors could also IPO, and at that point, Blue Apron still needs to justify why the market is better off investing in their company. By contrast, prior to its acquisition by Google in October 2006, Youtube was one among many social video sites, and neither it nor any of its competitors IPO'd, ever (source: I searched for news relating to "video sharing IPO" and found nothing prior to 2010 -- I could still be wrong about this claim, though). However, the operating costs of such a massive site (65k new videos with 100MM views per day, a mere 1 year after launch[0]) are substantial. If an IPO is just a way to defeat the competition using sheer survival tactics, I would have expected Youtube (or one of its competitors) to IPO or start fielding an IPO early-on. Maybe Google just bought them too quickly, as they were acquired in October 2006?

Does it mean that Youtube competitors like Vimeo must be profitable private companies in order to stay in the market? Youtube's pockets are, at this point, effectively infinite, so my sense is that Youtube competitors are not directly competing with what Youtube offers, but similar niches peripheral to Youtube.

[0]: https://en.wikipedia.org/wiki/YouTube#Company_history