When I first started the environment you used depended entirely on language. In the C++ and Python space, there was the vim and emacs divide. With Java it was more complicated. Some still used vim/emacs but a lot of people used Eclipse.
Now Eclipse was a real problem at Google because of the source control system. Java IDEs are primarily built to import binaries, specifically jars. In the outside world, these dependencies are managed via Ant (very early days), Maven/Gradle or the like.
At Google there's a mono-repo (Perforce/Piper) and you check out parts of it locally and rely on the rest via a network connection (to SrcFS IIRC, it's been awhile). This was neat because you could edit a file locally and the dependencies would just recompile (via Blaze).
So for Eclipse a whole lot of initialization had to be done and the IDE would fall over. A lot. It had a team of ~10 working on it at one point. Then somebody did a 20% project called magicjar. Magicjar took a Perforce client and built all the dependencies as jars that could be imported directly without parsing the entire source tree (which was usually huge). This made it possible, even preferred, to use IntelliJ, which is what I did. Magicjar was great.
Other people actually made CLion work reasonably well with C++ too. That was nice. This was a much bigger undertaking with many more corner cases just given how C++ works (ie headers and templates).
So checking out a client was relatively heavyweight, even with a minimal local tree. And, if you worked on Google3, you had to do this a lot. You might need to do a config file change. This was the real starting point for Cider because it was way nicer to do config file changes with it.
Obviously I don't know where all this went from there. VS Studio as a Cider frontend? Ok, that was news to me. Engineers being unhappy when things change and when the slightest thing works differently is the least surprising thing I've ever heard.
Oh it's worth adding that in my time many people didn't use Perforce (P4) directly. They used somebody else's project, which was a Git frontend for it, called Git5. I believe it was already being deprecated while I was still there. But Git5 modelled a P4 change as a branch so you could play around with your Git commits locally and then squash them into a single P4 change. I actually liked this a lot.