Yes, the browsers evolved very much beyond this original purpose.
Again, it did not happen without any reason, it happened for a reason. The purposes the modern browsers serve apparently are more important to their users than that original purpose!
Indeed, I believe there are obscure browsers that don't support any of this new stuff, and are only good for rendering plain old HTML. They remain obscure for the obvious reason: they cannot be used for what most people use the browsers most of the time.
One example of many: Backspace no longer taking your to the previous page because that conflicts with usage in web apps.