There is no point in that Crypto-only bookmakers are not regulated, so they can just take any customer they want. And you can open as many accounts as you want. That is why most crypto bookmakers will scam you sooner or later (if you are a winning player).

Recreational players don't need broker accounts anyway. It doesn't matter where they lose their money in the end. With the good odds in asian bookmakers, their deposit just lasts a bit longer.