> I also don't understand why phrases like "probably ok" are useful in
> this context. To me that sounds like: "it's ok for amateurs, who have
> little knowledge about Emacs conventions, to do it, because the harm
> will be quite limited, but real pros wouldn't do it because they are
> aware of some obscure problem that might arise even if only with low
> probability."
There are no obscure problems.
In this context, it means that probably nobody will be bothered by it. But you never know. There may be some user out there who gets enraged at the fact that they now have to add one line of code to their init file to prevent a package they explicitly installed from adding an entry to auto-mode-alist.