Does it matter if I use Ubuntu or Debian when I want to use Linux shells to achieve something?
Depends, I can give you an answer that fits all the distributions out there, because it does things like one would do it on Linux From Scratch; but doing it that way, would that necessarily be the right way?
I don't think so...
Or perhaps I tell you that on Gentoo you need to make a configuration change in some path; I am pretty sure that if you run Debian or Ubuntu that that configuration file is not necessarily in the same place, even locating that configuration file happens differently on multiple distributions. And if you are going to be bold and give either a LFS based suggestion or a suggestion that only fits another suggestion; then, you are simply degrading the distribution experience that the user has.
Then why do we even have the Linux tag...
Well, it's apparently NOT for cases where we do distribution related things; but rather, for cases where we look for something that works on software that runs on most of the distros.
So "How does one copy 10 random files from one folder to another?" would be a question I see as perfectly fine to receive a Linux tag; but if you come with "My system logger daemon doesn't start anymore, why?" or something along those lines, it really helps knowing your distro so we know where your configuration files, logs, commands for integrity checking and anything else are located.
The trick here is to not remove the tags, but rather to guarantee they are properly used.
Same story for Windows, a lot works amongst all supported versions; so, why force restriction?