Because tech has proven so oligarchical, so susceptible to absolute domination. Meta doesn't dispute the centrality of AI, so they fear a clear winner will eat their lunch at everything else. (You can see from their a bit silly experiments they think AI has important social media applications.)

It's a really good thing, though. The only I-gotta-hand-it I have for Meta. Linus Torvalds famously described the point of Linux not as "creating financial value" but sucking that value out of operating systems. If he hadn't, we'd all be paying exorbitant taxes to Microsoft and some commercial UNIX.