Yes, all valid points. And yes, particularly as a transport protocol it would, like other protocols lead to decentralized services. But perhaps I should clarify a bit and say that, HTML and the web browser have led the Internet into a place with lots of centralized services.

If we see HTTP as a transport protocol like UDP or TCP, then yes you're very right. But if we look at HTML and web browsers becoming denominate applications of the Internet, then I believe that's how a lot of this centralization happened.

If you look at the web as a series of servers, sure it's decentralized. But contained on those servers are a lot of centralized services, i.e. Facebook, YouTube, etc.