Any casino is very important for its reputation and if there are a lot of unjustified account blockages, there will be a lot of complaints in Internet. It's very easy to lose the reputation that way. And it is extremely difficult to restore it.
Now there is such a large selection of casinos that reputation is very important for any casino so that people choose this particular casino.
Casinos need users, because the more users there are, the higher the liquidity of the casino will be and the higher the prizes in this casino will be.