I suspect Planescape might have had a concept before vtm but it would have been warp in an attempt to keep players.I've definitely heard this before, that is that part of the motivation behind planescape was to respond to the appeal of Vampire and other WoD games. This includes the idea of having an urban fantasy game high on factions and storytelling. Planescape is obviously very much its own thing, but mid 90s TSR was definitely contending with the success of white wolf. Ironically, for me at the time, planescape was my gateway into vampire and mage.
I know a lass who would like mage but she might lose touch with the real would.