Transfers in and out would cause huge source-of-funds type compliance issues and fraud problems, as well as support tickets from users setting the wrong fees and getting scammed. They would've bought something like Bitpay long ago if people cared to transact in crypto. The reality is 99% are happy just to store it on paypal,coinbase, etc and be charged exorbitant fees and hope the price goes up.
The source-of-funds problem is solvable, otherwise companies like coinbase wouldnt be allowed to exist. Paypal just needs to buy some chain analysis service, and implement SARs and other related AML stuff.