Pretty interesting history behind the current status quo. Looks like GCC deliberately resisted an interoperable design in an attempt to exclude proprietary code integration. It's only natural that interoperable alternatives would emerge and threaten its dominance.

https://lwn.net/Articles/582697/

> GCC's developers have actively resisted allowing it to be modularized in a way that would allow GCC's internal representation of a program to be read and used by proprietary compilation tools or optimizers.

Learning about this changed the way I looked at all GNU software.

> Basic things like onboarding and spectating on other people's code being reviewed is pretty hard to do from a mailing list.

Participation is even harder. I made some mistakes when I tried to reply to people on the GPG mailing list because I didn't really understand how mailing lists worked. Thankfully a person made a bug report on the issue tracker.

I still don't fully understand how they work. Many times I thought twice before getting involved in projects because I don't want to risk accidentally emailing people directly instead of the list thread again.