That's especially true for PayPal now. Before merchants didn't have much choice. If PayPal continues to be seen as difficult and risky, the better-qualified merchants will be the first to shift to other services. That will leave PayPal with a much more risky customer base than they have now.
5-year ex-paypal customer (and hated being one the whole time). 6-month stripe customer (and happy every minute of it so far)