Because if you have laptops with Nvidia Optimus, distros like pop_os make your life much easier since nvidia doesn't give two shits about Optimus on linux, hence the famous "nvidia, f*ck you!" quote from Linus Torvalds.
Or if you have a brand new laptop with the latest Ryzen CPUs and the latest Radeon 6800M GPU with switchable graphics then you absolutely need a distro with the latest kernel to have a good experience on this new hardware.
Maybe I underestimate how difficult some distros make it to have some semblance of control, but my model of Linux is that distros are nothing more than bundles of packages as a starting point from which you can add or remove whatever you want.
So I asked why it matters if its 'pop_OS' or not since if that happens to bundle some driver, or Steam, or whatever, I assume I can continue not using 'pop_OS' and still install whatever it is if I want?
It just seems like an irrelevant detail, (and potentially not even a valid one? the more you do subsequently the less it 'is' that distro) outside of saying 'everything worked out of the box, didn't have to install a thing', which may or may not have been true, but wasn't what was claimed.
If you're using Ubuntu LTS, for example, you're going to have the kernel version it shipped with and the Nvidia driver version is shipped with. When Nvidia releases a new driver with fixes for specific games, as they do every couple of months, there's no guarantee that this driver version is going to be compatible with the relatively fixed version of the kernel that Ubuntu LTS is using so you'd have to wait for the next release to play those newer games.
Of course you could forgo the packaged kernel and build your own then grab the Nvidia driver from nvidia's website, but then what is Ubuntu buying you?
Ubuntu LTS with its 2 year minimums lifecycle is kind of a worst case here among desktop distros, but different distros among the 6 month crowd can run into this depending on how conservative they are about putting the newest core packages into each release.
There's also the question of the method of obtaining third party software. There's basically a divide here between the ports method (see the AUR for the most well known example) where users distribute a build script to other users that in most cases should be pretty simply cloning the upstream source and running their build script, or the third party package repository approach where you download a binary package and install that. The port has the advantage of being very easy to audit the packager's code (if not helping for the developer's) and generally not needing it to be rebuilt every time the dependencies do, but the third party package repositories have convenience and you could argue that relying on launchpad's moderation is not any more or less safe than relying on Nexus Mods moderation which Window gamers happily do.
