I would guess developers must be using a lot of "workarounds" without management's knowledge.
However, it maybe should not be a requirement. AFAIK nix allows you to install stuff as a normal user (and so does dnf on Fedora, but it depends on the package).
Only thing that annoyed me was when I did some work on an internal web tool (php+js) and had no php-fpm & httpd. But by now I've got a container for that.
I would guess, though, that having to change the prefix and default locations in all tarballs you download must be quite a pain. You can't install DEBs or any other tools either?
We use some external stuff like sqlite, qt,... but that's all versioned in our gits as well (-> easily reproducible builds). Since we sell a commercial product we can't just add random deps anyway. Plus, I think there is very little code that would benefit from being replaced by an external libs.
Relevant tools are on a global package list. We can get stuff added there on a short notice, and with little questions asked. Eg when I needed some lib for a FPGA dev kit that was a matter of minutes.
Uaaah, Firefox on Android is messing up the input again (can only append, not edit). I guess I should just hit that "reply" button then).