Because in reality paypal is actually pretty awesome (note: I work for Etsy which uses paypal as a payment processor, so I guess I'm kind of biased). The cost for the business, compared to maintaining your own payments platform at scale, is pretty reasonable, and the failure rate is pretty miniscule when you consider the amount of potential fraud that goes through the platform.

Paypal wasn't really designed to handle one off personal payments, it was designed to let small (and large) businesses accept payments, internationally and fraud free. This is ridiculously difficult (how many of you have ever written software that integrates with a bank? ugh.) PayPal does this exceptionally well and because of that many huge businesses are built on its back.

The reality is, in most of the situations that people complain about freezing their money, without paypal their entire project would've been a no-go anyway.

I do feel for people who legitimately have their accounts wrongly frozen (I am one of them, though mine was unfrozen after a few days), but you have to understand how small a percentage of people that is, and that you can't have a system without failure. Again, paypal's failure rate, when you consider what they actually do, is astoundingly low.

Edit: Just for absolute clarity - I work for Etsy and have zero affiliation with the blog from the OP, and it has zero affiliation with Etsy. Also these are my opinions not my employers etc.