This is not true either, as monks can use their supernatural abilities without a spellbook. Also, you should know that there is no canonical precedent for stripping a warlock of his powers. Because it is believed that the patron teaches the warlock how to use his powers. He can't make him forget what he's learned. In any case, the discussion does not make much sense, since in the next version of the board game, the warlock will choose his own mental characteristic, which, it seems to me, is very logical. It is a pity that the Larian will not introduce this innovation proactively.
Monks receive their powers from their faith...technically from their deities but more hands off than with Paladins who can actually call on their deities. Monk powers are in a way similar to warlocks whose patrons aren't consciously aware of them using the power.
As for warlock pact policing that is left entirely to the DMs...but the point remains warlock power is given. But in terms of a patron who isn't aware of the warlock using the power...that's probably a case where the warlock could do whatever without risking repercussions. And patrons like fiends who give power in exchange for the soul probably wouldn't care what you do as they are only interested to collect when you die...though if they become aware the warlock could realistically have a chance at becoming a deity they might object as that would essentially nullify the contract and they'd never be able to collect.
