>It starts by not looking into Windows through UNIX developer glasses.

People don't need any UNIX biases to just want multiple versions of MSVS to work the way Microsoft advertises. For example, with every new version of Visual Studio, Microsoft always says you can install it side-by-side with an older version.

But every time, the new version of VS has a bug in the install somewhere that changes something that breaks old projects. It doesn't break for everybody or for all projects but it's always a recurring bug report with new versions. VS2019 broke something in existing VS2017 installs. VS2022 broke something in VS2019. etc.

The "side-by-side-installs-is-supposed-to-work-but-sometimes-doesn't" tradition continues with the latest VS2026 breaking something in VS2022. E.g. https://github.com/dotnet/sdk/issues/51796

I once installed VS2019 side-by-side with VS2017 and when I used VS2017 to re-open a VS2017 WinForms project, it had red squiggly lines in the editor when viewing cs files and the build failed. I now just install different versions of MSVS in totally separate virtual machines to avoid problems.

I predict that a future version VS2030 will have install bugs that breaks VS2026. The underlying issue that causes side-by-side bugs to re-appear is that MSVS installs are integrated very deeply into Windows. Puts files in c:\windows\system32, etc. (And sometimes you also get the random breakage with mismatched MSVCRT???.DLL files) To avoid future bugs, Microsoft would have to re-architect how MSVS works -- or "containerize" it to isolate it more.

In contrast, gcc/clang can have more isolation without each version interfering with each other.

I'm not arguing this thread's msvcup.exe tool is necessary but I understand the motivations to make MSVS less fragile and more predictable.

Yes. Any user interface toolkit that isn't at least 10 years old should be ignored on windows unless you want to rewrite everything one day.