Which was the point of them making it in a web browser. Leverage that as a platform to make extensions/plugins easier to write and maintain and allow them to do more.
Atom is a more capable "IDE" than any other IDE i've ever used, and it's easier to create and manage plugins for. Yeah, there are still some rough edges and things that I hate about it (honestly the whole "hanging for 30+ seconds because you accidentally opened a compiled file" shit really needs to get dealt with somehow, every release they chip a bit off of it, but it is still annoying), but it's by far the editor i'm the most productive with (by quite a large margin).