Also, lots of places and software are "stuck" at HTTP/1.1 when HTTP/2 and 3 are already out. Why are they stuck at something that came out in 1997? Presumably

Also, lots of places and software are "stuck" at HTTP/1.1 when HTTP/2 and 3 are already out. Why are they stuck at something that came out in 1997? Presumably it would be far easier to upgrade/replace your webserver, loadbalancers and clients than replacing all routers on your ISPs.