> They would never make a Firefox/Chrome-tier abomination themselves

*coughicecatcough*

> I think the biggest negatives would be their core utils, I guess

And gcc, though I don't really have much against gcc, it's doing its job, just compilation takes unnecessarily long and binaries it spits out are unnecessarily large compared to say tcc for example.

> because many programs depend on it and can't be built with musl, I hear

It can't be used with SoystemD, which is really the big reason why Juan RP decided to not use it for Void Linux.

Though I would rather classify Emacs as an operating system within an operating system rather than a development environment, because it can do so many more things that has nothing to do with development, some of which you listed already.