I don't understand what the problem is: 1) you install ONE version of python, more can't coexist in your environment usually 2) then you install your packages

I don't understand what the problem is: 1) you install ONE version of python, more can't coexist in your environment usually 2) then you install your packages in a venv (because python provides tools to configure this) Only part 2 is a problem of the Python ecosystem, part 1 is a problem of any environment to run binary programs. It applies to C-compilers, node, ..., perl... Naturally, as most people involved with Python seemed to agree with that view, there was a lot of room for "improvement". And people got their improvement aplenty. Other people just realized that this is a general problem and nowadays instead of keeping around their /opt they now use something like spack. Which allows you to install a range of python-versions just fine. As well as C-Compilers. As well as perl-versions.