Do you noticed that there are many complaints recently about gambling sites blocking the accounts of some users. The user may have more than one account but maybe they do not read the terms of service before gambling. This is the ones that we heard of. There would be more than we did not know.
The first three gambling sites that I used which were local gambling sites, I did not read the terms of service. I use the same ISP to open 3 accounts for the first gambling site. I saw no problem because I lost money than win which makes me to to have a single withdrawal. Supposing that I won huge amount of money, they could have used multi accounting as an excuse not to let me withdraw the money.
It would be good for newbies and many people on this forum that are not even newbies to read the terms of service of the gambling site that they are using. Having more than one account is against the ToS of all or most of the gambling sites.
Even though we read their terms and condition I guess its up to the player how they will work around with the casino. There are some player just get deposited into the casino just to have the bonus rewards and they play afterwards they won a large amount and would like to cashout immediately without meeting the requirement bet of the casino.
There's nothing wrong with the multiple accounts just you don't have any suspicious activity for example self-referral and make a back to back transactions with the accounts as long as you just play regularly those accounts and does not have different IP address reason why prevent VPN if that casino does not support this base on their terms to prevent being suspicious.