Banning some casinos against players from certain countries is possible and also happens for fiat casinos. They don't allow that player, maybe because they can't say clearly in their rules. And players from these countries should be able to understand and not try to play because it will look pointless because casinos can easily block their accounts.
Another advantage of opening an account at a bitcoin sportsbook is that players can use the various coins available in the crypto by buying them in many places. They do not have to use fiat, although that option will remain with their account. Using bitcoin and altcoins for gambling gives gamblers the freedom to choose their coins and doesn't need to do KYC to play at certain casinos.
Every other thing you said is absolutely right, but about the KYC part, I think most cryptocurrency casinos require you submit your personal information and identity documents at some point, maybe they don't ask for it initially and just let's you deposit and play without any hassle initially and then if you go for withdraw, they will ask for it there.
So basically, no matter what geography you belong to and in what casino you are gambling, if the platform has a license and is centralized, you will definitely have to face the KYC phase at one point.