Direnv breaks referential transparency of the shell. I heavily use my shell history to riff on commandlines I've entered in the past. If direnv is in the mix, my shell pipelines sometimes have to have `cd` in them, often in subshells because that works better for me than pushd/popd.
pyenv/rbenv/asdf do the same thing, but you can have a "global" version pinned and do all your shell-related package installs there, so it doesn't end up being that bad. Though, this still breaks when I happen to be sitting in a directory on my system that has a .python-version file. All of a sudden my "global"ly installed python packages don't work. I greatly prefer tools like pipx / pipsi for this purpose (is there a language-agnostic pipx-alike? or is that nix?) because the shims they install usually work no matter what my shell environment/CWD is.
.... Maybe most of my ire is because my only exposure to direnv is because at least one repo at my day job uses it. For me it's not so much "customize your environment any way you want", it's "oh did you run that command from projectdir/foo instead of projectdir/foo/bar? That doesn't work". Debugging the interactions between people's individual poetry/pipenv/pip/rbenv/direnv/etcetcetc setups and project-based setups is the bane of my work life.
Tools like asdf, direnv, nix-shell, etc. just encapsulate the environment and help set up some guarantees. The referential transparency of shells is something that these tools help enforce, if anything.
I agree that frequent jumping between the fragmented environments is pain point in software development these days. That's due to a lack of tooling to support the new workflow, in my opinion. I hope enough people feel this pain that we see some solutions.
Having an expressive shell like https://starship.rs helps keep you oriented as a sort of HUD. Nix is definitely a life-saver, but you can probably roll your own nix-a-likes. Encapsulate all the "global" precious tools, hardening them against changes in the "local" shell environment. Whether through wrapper scripts, containerization, or what have you, the building blocks are there, the "best practices" are still being created.
Seems like a lot of duplicated work across all these plugins
(My favorite worth-1000-words picture about that is e.g. here: http://www.tshirtvortex.net/free-magic/)
Can you be more specific? Maybe something's broken.
I wish this was available out of the box to handle literary 90% of the tools.
Also, I typically pair it with direnv [1] for even more magic.
[0]: https://github.com/Banno/asdf-hashicorp
[1]: https://direnv.net/