Do you think it's possible to pay a new group of people and have them care as much as the people who met voluntarily out of sheer interest and dedication to their community? I doubt it.
Edit: not that I'm against paying mods, I support that. But replacing enthusiast mods with paid mods, I doubt that'll be adequate.
The obvious example here is /r/AskHistorians. Notoriously among the strictest subreddits, and an absolute treasure to read as a result. There is zero chance it could be maintained by paid staff without a serious search for qualified people.
There's a bit in Predictably Irrational by Daniel Ariely where he talks about social compensation vs. market compensation (I could be remembering the terms wrong). He asks how poorly it would go if you went to Thanksgiving dinner with your grandmother, and after eating the amazing spread you handed her a $20 and said, "That's for the great food, gran, it was amazing!"
Edit: not that I'm against paying mods, I support that. But replacing enthusiast mods with paid mods, I doubt that'll be adequate.