[mixedCase]

> You can have any number installed and either switch by changing the tools version file

Oh, that's cheating :) Nix can do the same thing! Derivations are just kept in the store until you garbage collect them. You can also configure multiple versions at the same time to present you with multiple binaries, which is what I was referring to.

> Again theory vs practice. In theory, sure, it depends on the plugin. In practice, almost every plugin lists every single released version to choose from. Which is much different from nix where the official choices are limited and you have to work to enable the rest.

In practice, nixpkgs supports every maintained version of most tools. Certainly far more tools than asdf can ever hope to maintain. If not, there's an overlay or flake out there to support it. Can you come out with specific examples and a usecase?