I think most companies put restrictions on some countries due to their license. I don't think they specifically hate any countries that block access for them. If there is an unlicensed casino, but it still has restricted regions, I would say that is bullshit. I know some casinos that are not licensed, and they accept players from all over the world. No geo restrictions, and you don't have to worry about them blocking in the future, which usually happens when players win something big and get blocked because they discover that the player is from a restricted region. Crypto and gambling, both banned in my country. Yet, most casinos in the world accept players from my country.
There are many countries which are restricted by many centralized platforms that have to obey laws in their nations and also OFAC Sanction List of the USA.
Here is the list.
https://orpa.princeton.edu/export-controls/sanctioned-countriesNo public and centralized platforms want to have big issues with governements and the USA. by did not obey this OFAC Sanction List by allowing people from those sanctioned nations to register accounts and use their accounts on those platforms without restrictions.
This principle is kind of very universal for all companies and not only online gambling companies.