Maybe PayPal is taking a responsible, business like approach to due diligenence.
If the only reason a customer uses a service, is that if they choose not to take responsibility for their actions, they will not get a "black mark" , I don't think they are a real asset to any business. As with all things, time will tell.
Also in reading PayPal's fine print their Pay in 4 system is not going to be offere to every one of their customers, just a select few who qualify. Then if they renege on a payment PayPal reserve the right to bring in the debt collectors and put a black mark on your credit score. Neither such things occur with an AfterPay account. You're simply blocked from using it until you pay up (yes there's a late fee) and no mark is recorded against your credit score.