Developers do have stakes in programming languages and programming tools. You, yourself, said that you don't want to invest in Emacs. Someone who has invested a ton in mastering Emacs at this point has a personal stake in it. He wants it to thrive and have high adoption.
That being said, I'm actually in the same camp with you, on both counts (this comment and your previous one).
My main problem with Emacs is that of mindshare. To clarify what that means, I'll use some examples.
Git has huge mindshare: if a new development tool appears, if it can integrate with Git, its makers will try to integrate it themselves. This generally provides the best and most maintained integration.
Emacs has low mindshare: if a new development tool appears, Emacs users have to integrate it themselves. Outside of the relatively small Lisp community, almost no upstream developer is bothering to offer Emacs integration.
I'm not sure I understand your example. Emacs integrates, it doesn't need to be integrated. It also has the best git interface I have ever seen (magit).
In a certain sense a subclass of Emacs users are the makers since it is a traditional Free Software model not backed by a major corporation. But that can be seen as an advantage since there is no single point of failure, and if GNU doesn't do a good job it can be forked, and has in the past (remember XEmacs?).
Practically speaking, the major disadvantage of Emacs is poor asynchronous/ multithreaded support. That's not an easy problem to solve but I do think it will get better eventually, and I don't find it a major impediment in day-to-day use.
Well, if you want a clear example of what I mean, Jetbrains makes a plugin for Kotlin for their IDE and another one for Eclipse. They don't make one for Emacs. The Emacs community has to make it (maybe they do, I don't know).
Look at any tool (except for GNU or Lisp stuff) and try to see how many of them have Emacs plugins made directly by the tool authors.
Eclipse, Visual Studio Code, Atom, etc., tend to have plugins made directly by the tool authors, in many cases.
