I remember that those were used for games like Travian (displaying time and resources), dynamic content (like blasting music on a webpage) and web chat (that's what I blame the most, because it was in demand).

Well, they didn't do that, but I can imagine another "standard and convenient" way could have been taken to add realtime notifications to a webpage - a set of tags for displaying messages of an IRC channel, sending a message to an IRC channel, and so on, with maybe associating actions (going to an URL? or maybe updating part of DOM, but without full agility of JS, just add/remove/replace tag by id) with events. Like refreshing a page on a message in the channel, but no more frequent than N seconds.

Combined with iframes (I'll admit I consider iframes a good thing, burn me at the stake), this could give you a pretty dynamic experience.

IRC is, of course, not secure, but maybe if such functionality were present and if it became popular, IRC over SSL would become normal earlier too.

Or maybe something like WS could have been standardized far earlier. For pushing events to client.

I agree about F5, but the effect of realtime changes was psychologically very strong.