I would say though it's kinda hypocritical that casinos enforce this rule sometimes to withhold big wins. At least they should close the account and teach a settlement with the punter to find an acceptable solution for both parties.
That's my problem with the casinos too as they mostly enforce this rules when someone has won a big sum from the casino. There are many other multi accounts but they aren't doing anything about them until they have a reason to denied a player of his win. They're being greedy because some gamblers won't know they have multi account because they have forgetting about them for many reasons. I have opened an account with a casino because of a giveaway I won and need my username to claim my price, after many years the casino became popular I wanted to gamble on their casino and can't remember my email or password hence I needed to create a new account with them. If I was to be lucky and win a large sum, they'll then use this rule of not having multi accounts to denied me of my money when I didn't do it Internationally but my side of the story won't be held then I lose.
This would really be only happening into those casinos that arent that much popular or not known on which they would really be having those kind of shady requirement or enforcing KYC or possibly making up some issues
on the time that you would really be hitting up some jackpots or huge wins on which those reasons would really be keeping on piling up as if its obvious that they are really that trying out to not for you to be able to make those withdrawals. As for probabilities into those old and known sites then it could still actually happen because we've seen some platforms do still facing up some similar issues too but the good thing on dealing up with
reputable sites that it would really be that eventually getting that resolved out in compared into those new ones on which you cant really be having that assurance.
Most of platforms will really be that allowing 2 accounts or even more, just like been said by most people that as long you wont really be making use of those new accounts or other for the sake or purpose of cheating
or abuse then you should really be just that fine but if you are doing it for cheating then expect that they would be locking up those accounts and the funds inside through it.
This is why it would really be that important that making some self realizations on how things works and this is why it would really be that relevant on reading up TOS whenever you do
decide to gamble.