My thinking is that some editors tend to be fashionable. I don't mean that negatively, just that their mindshare is transient until proven otherwise. They have a subset of users that are not massively invested in the platform, and will move to something that looks more interesting or more secure/active/etc.

If that subset is large enough such a migration can harm the ecosystem: less users, less developer mindshare in bugfixing or plugin development and so on. It can then work like a run on the banks where people get out before the problem gets worse, making the problem worse.

Interestingly, vim is often one of those editors: when TextMate was originally dying (pre open-sourcing) there seemed to be a new "why I'm switching to vim" or "how to set up rails dev in vim" post every day. I'd wager that a lot of people moved to vim as a result, then bounced off again.

Because there are many annoying small bugs that prevent the editor from being completely useful.

Like what? Haven't found any in the 2+ years I'm using it for Python, PHP, JS and Go.