Maybe because 1) FB represents a level of success aspirants hold in high regard 2) FB is a marketing/monetization platform startups find difficult to ignore

I find it hard to get excited about this.. probably will get cancelled in 6-9 months after languishing a bit.

YC is pushing almost 6 years since their last true successful company. They’re no longer pushing innovation but, smartly, niche markets. That’s distant from the universe of what FB is.

An alternative hypothesis is that it takes that long or longer before you can really see that level of "success".