Sellers adding for PayPal use is plainly BS

Just offer what you are willing to pay for the product,shipping and Paypal. The seller is no more responsible than the buyer to pay fees. 

Actually I think you will find the seller IS responsible, after all they are getting the benefit of receiving payment IMMEDIATELY.  PayPal are not just going to give that service away.
Pretty sure it is in PayPal TOS that the seller should not try to pass on the fees to the buyer. Or words to that effect.
Better just for seller to never even,mention PayPal fees as it does cause many to just pass right away

I’m not sure I agree.  The buyer is getting the benefit of being protected and we all know PayPal tends to side with the buyer.  I usually offer PayPal and the option to send a check or money order.  You buyers sometimes need to take a leap of faith.  I’d rather wait for a check to clear any day than get paid immediately via PayPal.  And no, my items I sell are as I advertise so I don’t need PayPal, but some of you buyers do.

If I was not prepared "to take a leap of faith" with certain sellers  I would not use PayPal as friends and family so the seller incurs no fees.
Have done that with the last 3 sellers of fair priced items I have purchased from here and audiomart.
No buyer protection in that case.

It's also possible to charge nothing for the item you're selling, provide free shipping, and charge $2,000 for Paypal fees.