Well, to be fair, it was disabled because it mostly didn't work correctly in a wide amount of circumstances, because a lot of HTTP/1.1 servers didn't support it

Well, to be fair, it was disabled because it mostly didn't work correctly in a wide amount of circumstances, because a lot of HTTP/1.1 servers didn't support it correctly. Not because people didn't want better performance. It was bolted on and HTTP/1.x lets you get away with an incredible amount of stuff[1] while continuing to "work". It is also another thing that introduces head-of-line blocking; and that one isn't fixable even if the servers were. Moving multiplexing directly into the "data path" of the protocol was the correct move in the case of HTTP/2 and later, because you can't get this part wrong and still have things work; multiplexing is simply a core feature of the system. This is true of many other things as well. [1] Stuff like this is guaranteed to happen IMO because HTTP/1.1 is a perfect example of "deceptively complex." Everyone says that HTTP/2 got complicated, but HTTP/1.1 was already incredibly complicated to get working reliably and efficiently. The difference is you can't write an "HTTP/2 server" in under 200 lines of code that ignores 99.9% of the whole specification, while you could get away with this in HTTP/1.1. The /2 spec was, in this sense, largely an admission of the complexity of the problem, which protocol developers were already acutely aware of.