1) Think from their perspective. They have very little upside for integrating with cryptocurrency platforms. It adds nothing to the bottom line. If anything, it subtracts from their bottom line, due to the added compliance work required to prevent crypto money launderers.

2) Stop saying crypto is decentralized. The vast majority of cryptocurrencies are mined by a small minority, and most participants have zero say in the direction of each currency. Yes, you can have a "decentralized" architecture, but not "democratization". Crypto-space ended up with an oligarchy.