It's also easier to buy on Paypal since banks trust them and most people have some PP income already.
Not all banks are too trusting in online transfers like PayPal. There could be some times that a teller or the bank itself will question your transaction there. And if you'd mention crypto, bitcoin, etc. there were some cases that they're considering it as a red flag.
I don't know where you are living but I'm very curious to know in which country banks trust more crypto exchanges than Paypal. It's the first time I read such a thing to be honest. Cryptos are unfortunately still unavailable on Paypal in Europe, so I don't know how it works actually
I am speaking in a general case that it can happen when the bank asks about where the funds came from and the user says it's from PayPal but asks for more details and suddenly slides some words about crypto, that's how things could go worse for that instance. I've read in the past that there were some cases about that but that doesn't mean that it can happen to all of us.
if Paypal allows you to make purchases with your Bitcoin balance then it's ideal because you don't even need to exchange your cryptos for fiat and to make withdrawals towards bank accounts, or to buy gift cards with your cryptos in order to make your purchases, you can do that instantly without wondering what will happen with your bank and/or your exchange account.
I agree that it's a good feature if your only purpose is that. But if for long-term purposes, much better to withdraw after doing a successful purchase day. I also remember the days when there was a service that allowed people to use Paypal funds to buy Bitcoin, I forgot the name of it but it was a lifesaver long time ago for problems like these.