>I'm not from the US and to me PayPal was always only a way to avoid filling in credit cards details on (random) websites.

And this is the answer.

Paypal's existence comes down to the fact that they are the sole "legitimate" vector into the US financial system for a vast majority of the rest of the world. Because that's such a massive financial incentive, they can basically treat users however they wish and get away with it.

Brewing up space for that next startup who respects their users and works in the same marketplace ;)