This is not a question, and it certainly has no answer in F.A.Q.

Here's a more comprehensive warning. I hope Lichess will start to use it. If it doesn't seem complete, I can add some.

Warning: letting time run out instead of resigning does not help. It will only net you this warning, not even pity points. It does not harm your opponent in any serious way, because Lichess games are not FIDE rated and nobody earns any money from them except maybe when streaming. It only annoys those who are very very very easily annoyed - admittedly there are quite a few of those. But they would be annoyed by something in any case.

Admittedly there are quite a few of those.

Here's also a short version:

Warning: letting time run out instead of resigning will not help.

Like those annoyed enough to make a thread about it, perhaps?

Hardly. This is purely for the benefit of those who think they gain something by trying to annoy others.

Who in the world thinks they "gain something" by trying to annoy others?

How about "Hey you rude dumbass either play or resign"

I see a lot of the stallers avoid the warning completely by just stalling until their time is below a second and then resigning. Does Lichess still catch them?

All of them think they gain something. People generally don't do anything just for the sake of doing it.

OK, letting time run out isn't actually doing something, they probably do something else meanwhile - you may have a point, MrPushwood.