Matrix was influenced by the traditional URI schema approach however they also used an inverted URI to have the most significant segment be the first segmont. This is why it has a prepended segment followed by a : and then a URL.

The relationship the URI is describing is homeserver owns user and traditionally we might go homeserver:user I'd argue it is obvious to just invert that into user:homeserver. See Java, dotnet, etc reverse dns naming conventions.

A matrix room is not at a URI, it is on every homeserver that participates in the room. I am not talking about Lemmy and its garbage entirely incorrectly semantic URI scheme. Matrix rooms are globally uniquely identified, and so the room URI only describes the idea of the resource of the room. room:homeserver.

The prefixes are an obvious and neccesary evil for parsing them out of unstructured text. A requirement for most users.

ActivityPub and related went "fuck everything, fuck reason, the web is fucking amazing" and came up with their own flavor of stupidity. Emails use an ancient first attempt at a URL. A URL. What does the URL do? It is explicitly intended to tell you which server to contact. People are going "yeah but email!1!!" entirely moronically ignoring historical context.