I agree with you there. I don't remember which it was, but one of the runtimes managers (was it pyenv, rvm or nvm?) wrote to my .bashrc and .zshrc without asking for permission to do so, instead of just telling me the locations it wants me to include in my $PATH. I don't do path munging in my zshrc, rather, I source a different file that I use to manage this stuff and set up a way to avoid duplicates in $PATH and only adding things to $PATH when they exist so that my shell configuration doesn't do anything dumb when used across multiple computers.

Well, I'd rather their attempt at writing to my shell config breaks.

This is one of the many reasons why you should, if you haven't yet, manage your dotfiles with version control. Many tools assist in giving you some sugar over the process, I use homeshick which will move files away into a git controlled folder and create symlinks.