WordPress is very nice until you hit a niche problem: the media library has a lot of hooks that are not applied on the backend (and the media library itself is seriously dated); the XML library that can't handle a newline before <xml; while there are option for custom comment types, it's not actually supported; the REST API is a gigantic security hole; no database abstraction layer; etc.

I'm having high hopes for the ClassicPress fork to eliminate these bumps, but the future of WordPress.org will be interesting, especially that gutenberg breaks backwards compatibility, which breaks a lot of plugins, meaning you either go Classic Editor and your plugins, or Gutenberg and, maybe, some of your plugins.