Yeah can't even get paid without it. Believe it or not a lot of sites rely exclusively on Paypal. Lot of smaller businesses use it because it's easier and cheaper then trying to build your own online payment processor. Tell truth I used it on my own sites when I sold things online. If I remember correctly Ebay was the first to make it the way to pay with them. I only remember that because its how I first ended up with Paypal.

Of course this was before Square, and Stripe was available.