Here is a press release from cryptocoinnews.com https://www.cryptocoinsnews.com/breaking-paypal-merchants-can-now-accept-bitcoin/
Did you actually bother to read the article you linked to?
It is talking about Paypal merchants accepting bitcoin (via braintree who they bought) as a form of payment
(Why would anyone do this when Bitpay has 0% fee is beyond me lol )
Not about Paypal merchants converting paypal balance to bitcoin as the OP here wants to do
-----------
as for wesellcrypto.com I do not know how they do it, maybe Paypal haven't copped on yet onto them, seeing as to how they want all sorts of documents it could very well be a way of gathering identity documents for all sorts of nefarious activities.
It's depending on who you trust, if you talking about documents for verification, they do it to make sure you are the owner actually most of websites are doing this since PayPal is so risky.. I do not know this website actually but most of exchanges doing it.