I also learned that there is something called a dormancy fee or maintenance charges on those inactive accounts which covers for administrative cost incurred by those accounts. I learned that the deduction is from the remaining balance in the account. What about inactive accounts without any balance? On the other hand, what type of fee is charged on an active account?
I think it depends on the gambling website on their stipulated ToS on what will happen when your account becomes inactive.
There are casinos that do not have any restrictions when a certain account becomes inactive; whereas there are certain casinos that may suspend/terminate your account when it reaches an inactivity level beyond the threshold on what is stipulated.
Though this may be the case, I do think that inactive accounts are put into stand-by to the point that it is not fully terminated even without any movement for a couple of months.
The reason is because once you have submitted your KYC documents, such is already binding to that account.
Also, a person who quits gambling may decide to play again after a long hiatus- submitting the same KYC documents is not only tiresome/hassle but it may also pose future problems (e.g. proving that the KYC documents are yours, etc.).