The Web has been a very popular development platform for a long time, but that time has been characterized by intense competition between browsers. It's a bit different from most platforms which are clearly dominated and guided by a single player.

So it's a bit more of a "wild west" and it does represent wasted productivity if you look at it that way. You can also see it in a more positive light as a tradition of taking ownership of the tooling and continuously improving it. Because there's no central authority setting a course for the future, progress is through competition among solutions developed by the community.