Small e-commerce operators pay through the nose and a hidden fee is that most e-commerce operators have almost zero defense against a refund claim because their transactions are card not present. The refund is often a penalty plus the full amount of the transaction (incl. the fee) too. 
PayPal doesn't work for many people; frozen funds, deplatformed - basically very very few rights and high fees.
The question I ask any FinTech is whether or not the current centralised ways of doing things add enough value to the economy relative to what they take out; I'm not convinced that's the case for much of the transactions that are going on.