You can also use it pretty comfortably in vim (with a couple of plugins) https://gist.github.com/mhitza/a00d7900571e9f13bac2bbf4a203d... . I've used this setup to write both Guile and Chicken Scheme programs.

The LSP is the biggest missing piece for these niche languages.

In my perspective the reason why it still hasn't taken over is because it's not a focused and supported effort. In my understanding Guile should have been "the GNU scripting language" but the integration is nowhere near what a universal language would be (GNU Make integration is disappointing and totally not what I was expecting).

Then the fact that the project seems to be hopping between different directions (last time I checked they wanted to be a runtime for more than one language).

And they also lived their own Python2 -> Python 3 "migration pain". (In my above gist, I specifically had to compile Guile from source because at that time some application with a hard dependency on Guile2 wasn't getting updated in Fedora, which was holding back the Guile v3 rollout).