Even though you are correct to a very great extent yet sometimes it might occur that the casino is mistaking somewhere, because I have seen and accusation somewhere not this forum where a casino apologised to a user for accusing him of having multiple accounts however it was all a misinterpretation of information from the casino server, so I can still say that not even the casino is immune to mistakes. However not also understand estimating the fact that people become greedy sometimes to go against the terms of services of a casino.
This is one bad side of Sybil check there has never been anywhere that this tools use are most accurate most at times they might caught a wrong person, I don’t I have seen casinos that actually will boast that there Sybil checker tool is most accurate that’s why they always provide the options for the players caught wrongly to actually appeal and if the proven wrong they simply apologize sits well with me. Sybil checker tool are usual front-end tools for onchain analysis and this is definitely going to pick out some linked accounts which might not be Sybil.
Some people use Tor, VPN to change their IP address and location. In such cases, casinos ask them to complete KYC, where the abusers fail. Even if they submit fake documents, their documents gets rejected.
Sybil checker tools have gone past using geological locations as Sybil checks. On chain transactions are most what is use now most especially casinos who run contests and giveaways since it is them that you see cheaters mostly coming for