Give me 100 rubles, and I’ll make you a king!

In the second case, it is assumed that they themselves would not mind using donations. And in the third, it's as if it doesn't concern you.

The point is clear.

This is a game, and it should still be a single experience that shouldn't involve anything extraneous. Like money from the real world. IMHO.

The game itself is often a commercial product that requires a monthly subscription fee. And, like any service, it can (and should) provide other features for user convenience.
MMORPGs, by definition, do not have role-playing or any plot, except for what the creators and fans write on their websites, which is not even present in the game itself.

This proves that in MMORPGs, skill in the game doesn't matter. If you have cool gear, cool skills, and a lot of HP, you are invulnerable.

Skill matters, though. If you give a fool a character, even at level 100+, they won't be able to do anything with it.
By the way, you level up skills yourself, so what does this have to do with it? HP is also determined by skills. And you find the gear yourself.

Not really. But if you get 100 per day... then it's a disaster.

Why? You pay for "leveling up" and gear once, and that's it.