Simply because is better to pay 3% fees than risk being with accusations of money laundering or illegal trafficking.
PayPal and neteller are under KYC , so every transaction you made will be traced.
Safest way is to sell it by yourself on Neteller or use trusted service like Bitpanda (for neteller). Or use Something like kraken for bank tranfer
P2P Neteller & Paypal are reversible. P2P Bank trasfer may came from stole account or fund can came from illegal acitivity....
Only an idiot would accept paypal and neteller without knowing how they work and why would I pay exchange fees instead of making a profit?