The idea that the monsters are real to me is antithetical to the entire idea of Scooby Doo.
That's why it was called the Mystery Machine and not the Monster Machine.
We wouldn't have the "Scooby Doo", ending otherwise.
Yeah, I hear you and all but as someone who was always been fascinated with the supernatural, I liked the cartoons mostly because of the monsters and ghosts they faced. The notion that they were morons dressed up in costumes who had stupid motivations I didn't care much for. Once the masks came off and the deus-ex-motivations dropped, then my interest flew away. Ironically, the one incarnation of Scooby Doo where the creatures were real, namely the 13 Ghosts Of Scooby Doo, the show then turned into Ghost Busters.