The original crappy design is definitly a problem with JS: the typing/testing, the lack of namespace import, the emptyness of the stdlib. Half of the problems we have today are directly correlated with this.

Most of our tools are not here to make things better, but to avoid sucking too much.

So yes, forward compat is an issue. But that's hardly the one I'm complaining about. I'm really ok with not being able to use spread, but I can live with it. I'm not ok with having to use npm + webpack to download, install, isolate and bunddle a remote lib to do a leftpad.