You are missing the big picture who develops them, pays the salaries of people in the trenches, implement LSPs, and whatever else around the ecosystems.

Example, Java, .NET, Go and co are FOSS, how long do you think they will keep on going without their overlords?

For complete alternatives we need to go back to the cold war days, where programming languages were driven by vendor neutral standards, and there were several to buy from.

As it is, it suffices to take the air out of existing FOSS options.

Even if you quickly point out to GCC and clang, one reason why they have dropped implementation velocity from existing ISO revisions is due to a few well known big corps focusing on their own offerings, while other vendors seldom upstream stuff as they focus on clang.

EDIT: As I missed this on the first comment, same applies to the big FOSS OS projects, most contributions to the major Linux distros, or the BSDs come from non European companies, there is naturally something like SuSE, but then we get into the whole who is allowed to contribute, security, backdoors and related stuff.