Even ignoring the fact that I don't like paypal's business practices, and I believe paypal as a service should not be needed at all, I cannot ignore the fact that if I use paypal, I will lose access to my money and I won't be able to do anything about it. Even when using paypal purely as a proxy for buying stuff (with no money in the paypal account itself), I've had accounts locked for no particular reason (with payments denied to the seller, but me losing the money), which meant I didn't get my product and precluded me from doing business with the same seller in the future.
Paypal is a huge liability. Fortunately, it can be avoided for almost anything that matters, sans Ebay.
Sometimes I need some obsolete, unique product that is available on both Ebay and Amazon (3rd party seller), but it's more expensive on Amazon. I buy it from Amazon each time just to avoid Ebay.
That said, they do not make it prominent and I often have to explain to my users how to find it.
Paypal has historically sided with the customer close to 100% of the time, mostly because they are not a bank and therefore are pretty much powerless when a customer issues a chargeback. That's why fraud is rampant. If its trivial for an unethical person to steal things on a regular basis using paypal, because sellers have no reliable form of recourse, I can be pretty certain that as an actual honest buyer I'll practically never have to worry about getting screwed over by a seller.
I remember Marco Arment commenting on this.
All the while, the funds in your account add up - yet you can't touch them - and you have to deliver product to customers.
It can get very uncomfortable, very quickly. I thought I was safe with your advice, but still found myself recently with 6 figures held in a PP account.