I do agree that differentiating between competitors is tough though. On the surface all of these companies look about the same. They try to cater to different segments - health conscious, upscale, etc, but I'm not sure how effective this is.
For a while we ordered mostly takeout which was both expensive and unhealthy. We were able to start cooking for ourselves for a bit on our own, but eventually the weekly meal planning and shopping run got to be too much of a burden. That's where we found Blue Apron which had us eating healthy for another ~6 months. During this time we tried Plated too, but that week was guest recipes from some magazine and they were poorly timed and included practically inedible ingredients. After 6 months work situations changed and we just didn't have time for an hour of cooking 3 times a week. Since then we've been using Munchery which we're very happy with.
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.
A better analogy might be Groupon (IPO'd 2011) or GrubHub (IPO'd 2014). Both of those were in similarly indefensible industries - GrubHub even in food delivery - and they both IPO'd basically because having capital gave them a competitive advantage over competitors that didn't, because it let them not-die and continue attracting customers with subsidized prices. Neither was kind to public market investors, but it was absolutely the right choice for founders & early investors who got out (or in some cases, were forced out).