It isn't a conflict of interest, it's risk mitigation. Banks and payment processors constantly analyze which categories spawn the most fraud and at a tipping point they ban the category completely. This is why it's incredibly hard to fund an online casino account with a credit -- or even a debit -- card without using some shady 3rd party go-between.

This bit me with Coinbase 7-8 years ago when I was trying to buy $10k of bitcoin -- they'd only allow bank transfers, and only $100 at a time until you were "established". I gave up (and lost a lot of profit because of it).

The quasi-anonymous nature of crypto means that fraud is rampant. For better or worse payment processors and banks have decided they'll make more money banning crypto unless the whole transaction is within their ecosystem. It's not great but I get it.