I hear you that it feels like something is off. The lack of diversity feels like we're losing robustness in the ecosystem. But it can be a good thing too. A lot of security issues are concentrated into one stack that is very well maintained. So that means everything built on top of it shares the same attack surface. Which yes means it can all come crashing down at once, but also that there are many eyes looking for vulnerabilities and they'll get fixed quickly. Similarly perf optimizations are all shared, and when thing get this popular can get pushed down into hardware even.

It's not like we see a lot of downsides that the world collectively agreed on TCP/IP over IPX/SPX or DECNet or X.25. Or that the linux kernel is everywhere.