Linux

I would recommend Linux Mint because, first, it's the one everyone says, and second, it was the Linux OS that I started with, fresh off Windows.

Both are bad reasons to pick a distro to recommend. Better reasons would be

1. You got some experience with that distro and you're willing to help the newbie in question, with issues that they might have.
2. The distro offers sane out-of-the-box defaults and pre-installed GUI software.
3. The distro is reliable, and won't give the newbie headaches later on.

why not just skip the middleman and get right into the distros that have a bit more meat on them?

Because a middleman distro is practically unavoidable.

You don't know the best distro for someone else; and if the person is a newbie, odds are they don't know it for themself either. So the odds the person will eventually ditch that distro you recommended and stick with something else are fairly large.

Cinnamon vs. KDE Plasma

I have both installed although I practically only use Cinnamon (due to personal tastes; I do think Plasma is great). It's by no ways as finicky as the author claims it to be.

Plasma is more customisable than Cinnamon indeed, but remember what I said about you not knowing the best distro for someone else? Well, you don't know the best DE either. You should rec something simple that'll offer them an easy start, already expecting them to ditch it later on.

So, why don't I just recommend Linux Mint with KDE Plasma? Well, the cool thing about abandoning Cinnamon and embracing KDE Plasma is that it unlocks a ton of distros we can pick from.

That's circular reasoning: you should ditch Mint because of Cinnamon, and you should ditch Cinnamon because it allows you to ditch Mint.

Bazzite, Novara, CachyOS

Or you can install all those gaming features in any other distro of your choice.