The family of OneBookshelf sites (like DriveThruRPG, The Dungeon Master's Guild, DriveThru Fiction, Wargame Vault, etc) all share a common architecture, and in fact a common database. Your user account on one will allow you to log in to any of them. Your wishlists on one site are actually fully universal and can contain titles from any of their sites. You can actually open a title you find on DriveThruRPG on Pathfinder Infinite, or any other OBS site. Choosing a "preferred marketplace" is just a quality of life feature for Deals of Opportunity users, as often we have sites we prefer. For example, I use DriveThruRPG most often, and would prefer to view titles there. This simply ensures any title links on the website or in your notificaiton emails open titles on a website you prefer. You can change this selection at any time