[rcxdude]

In most people's mind extension = optional = afterthought. Especially this is the case if you cannot guarantee that something which supports the protocol actually supports the feature then it's difficult to use that feature. The main point is that the mentioned features are no longer optional for a 'chat protocol', any protocol which does not have them as core or required features is not going to be considered meeting the requirement of 'chat protocol'.

[Andrew_nenakhov]

Most people's mind do not care about protocols, they think of products. And speaking of products, every major xmpp server implementation I know (and I know at least five) supports all these features.

Also. You don't really need any of them to send messages between servers. All this stuff matters only for communication between your clients and your own server.