yes but so do other huge game companies on cosmetics, in game items, other spin offs. I agree it's not as easy but right now even doing this is unusual for most companies.
No they make most of their money taking cuts from games sold on steam, afaik. CS2 probably makes lots too but I really hope TF2 doesn't. (I'm still salty they left TF2 to rot)
I just did a minimal amount of googling and this is absolutely not true. Micro transactions have outpaced full game sales by almost 3:1. The entire model of free to play games relies on microtransactions. The biggest games in the world right now are f2p games or paid games with f2p models. I dunno where you're getting your info from, ancedotally, I'm sure, and maybe you just don't play games like that... But the rest of the casual game player population absolutely does.
That first point is not true at all. There are entire games built around the paid cosmetics. League of Legends and everyone who follows that model for example. There are more than a few, but you're right on the second point. I mean it's not nice to call people stupid, but I suppose that's not what we're discussing.
My first point is that there are very few companies that actually make money from this, not that there are no companies. Riot games is one that does make money.