I would argue that Buffy certainly is a superhero show (especially given how episodes are strewn with comic book references and superhero tropes) but that's beside the point...I agree that Smallville inspired those shows but they hopped on the big bad wave because of Buffy and other shows inspired by Buffy.
Out of the 10 seasons, there were only maybe 5 season-long big bads. Jason Teague, Brainiac Lex, Doomsday, Zod, and Darkseid.
There were definitely recurring antagonists like Slade Wilson and Lionel Luthor, however the discussion here is season-long arcs solely reliant on one main villain. Smallville really never had that until the later seasons, and by that point it was already a huge part of tons of TV shows.