We're talking about Web browsers. Technologies that try to integrate into Web browsers specifically but don't have a good compatibility story with the platform haven't had a lot of success.
In some ways they do, but they are also nonstandard, with the downsides that that brings. Neither overall approach is perfect, it's good that we have a combination of both in our field.
Why get hung up on the fact that something is non-standard? Things don't just pop into existence as a standard way of doing things. Some core group of people has to agree on them and then away we go - we have a standard!
That's why everybody should actively use non-standard things that they want to become standards.