Disagree. "Everyone can edit" does not mean "everyone has equal access to all facilities". A new user can't access admin functions, an admin can't necessarily access the OTRS (volunteer email) system, and so on.
I don't see a problem with saying "we have made arrangements with these suppliers to provide access to sourcing material as a paid service to anyone meeting criteria X. We also make it freely available to Wikimedia editors who meet criteria Y".
At a last point, one might even have a select team of users with appropriate skills, who are granted such access, purely for the purposes of checking and locating claimed citations.