As far as i know all sellers have to have a Paypal account  - so ebay isnt forcing people to use it but not far from it. If Paypal is the preferred payment method i think the listing should state:

errrr NO all sellers do not have to have a paypal account. Aussie sellers must have PayPal or PayMate or offer C/card facilities

USA sellers must offer an ON LINE payment method

German Sellers can insist on bank transfer,

all eBay sites have different payment methods, NONE of which has paypal COMPULSORY.