It's because underage kids use it and get caught when someone disputes on them for scamming and Paypal catches onto their account and they get their account locked for not providing proper information to have a legit Paypal account.

It's because you can chargeback. Sometimes I have to pay transfer fees since my Paypal is not verified.

I got permanently limited over my first ever transaction in which was to my brother, was only 5, and PayPal claimed that the way I did business was unsafe, therefore they had to remove me from their service and unable to appeal against nor make a new account with my name lol..

It's the only one I use. I just don't like the waiting period when you have a dispute/escalate claim with someone. I'm not to familiar with other forms of payment besides PayPal.

I personally love PayPal because it's much easier to use then trying to buy something with a CC.
Some people don't like it because of the shear fact that it takes some time to set up.