The two main things that are limiting are that you can't take advantage of the unique strengths of the particular device you're running on
There was a reason I wanted specifics. This is a generic comment and it generally isn't particularly accurate anymore. Do you know of any specific things that would suffer on any specific platform?
performance always (and inevitably) suffers
Again, not specific, and generally extremely far from the truth. Yes, Javascript runs slower than native code, but that isn't necessarily an issue. It depends on what your app does. Many, many apps are not calculation heavy, they collect data from a back-end server, present it to the user, allow the user to alter the data in some ways and then send the data back to the server. Any slowness in such application will be caused, by network slowness in almost all cases. In other words, the performance of the underlying GUI language is mostly irrelevant as long as it is fast enough, and Javascript is, for a huge number of applications.
So, at this point in time you have not given any kind of arguments that supports your position.
Have you developed applications in Javascript that suffered performance wise? Have you developed any mobile applications that you assume would suffer performance wise?
It's easy to parrot the "wisdom" of others, that's why I asked you to be specific. You weren't.