You have said it rightly it is KYC that casinos used to scammed gamblers as you said. Lolz finally you have submitted to their conditions and claim your prize and we thank God that they responded to you documentation very fast for you to claim the prize and move on. Because this is where they (casinos) use to withheld winning prizes by gamblers and ask them to fill forms and update data and upload documents and if the gambler could not provide any information there the prize will be forfeit or they close the account. And all those information were not asked at the beginning. There are good casinos but the bad ones are over shadowing them. Not that KYC is very bad but it is the casinos making look like a very bad something. And probably casino 500 have a very good responding system and that was why you case was speedy.
Even though users have opposed not uploading documents but they have no option to withdraw funds and claim rewards which are given to users who have valid KYC documents. However, I don't know 500 casinos yet but 500 casinos have been added to the list on the main topic and they are very fast in the KYC verification process, so other top casinos should also do the same for service priority for users, don't make KYC verification difficult as they will tend to find another top casino that is friendly in service and quick to handle any problems.
Well, one thing that we must understand is that, every online gambling casino have their strengths and weaknesses, even if a big casino delayed in processing kyc verification request from their customers, know it that, there are other areas where such a casino is definitely better than the casino that processes kyc request faster for their customers, this difference could be in game odds, more winning ratio due to lower house edge and so on..
So in the end, if you abandon a good casino because they fail to process your document verification request fast, you will at the end of the day still find yourself back to the same casino because, there is something they have that can't be found on another casino.
And as for 500 casino, I know this casino even though I have never played there, I've seen their signature ad on this forum several times, and their administrator on this forum is quite active as well, its definitely a good casino, but like I said, I have never played there.