So the problem with the Indiana Jones movies is that there were archaeologists in academia in the movies instead of Indiana Jones having to face off with Montana Jones and Mississippi Jones at every dig site? PCs should be adventuring, and maybe some evil NPCs should be out there adventuring, but I don't see how it adds to most settings for there to be a huge number of adventurers running around, and it seems counter to the assumptions made in most D&D adventures. I think it rather adds to adventures if there's a cleric in town who can raise dead, but never has, never will adventure and leaves that to the PCs. Megadungeons seem to be the main exception, where it's logical and fun to have multiple adventuring parties running around the same setting.