Similar story at my prior job. Heck, we still had one package that was only built using 32-bit .Net Framework 1.1. We were only just starting to see out-of-memory errors due to exhausting the 2 GB address space in ~2018.

I love the new features of .Net, but in my experience a lot of software written in .Net has very large code bases with a lot of customer specific modifications that must be supported. Those companies explicitly do not want their software framework moving major supported versions as quickly as .Net does right now, because they can't just say "oh, the new version should work just fine." They'd have to double or triple the team size just to handle all the re-validation.

Once again, I feel like I am begging HN to recognize not everyone is at a 25 person microservice startup.