He started doing it 34 years ago, long before it was “cliche”. And he was excellent at it.
As Cliffy said, he was an artist who produced a brilliant body of work. He was an underground comic artist on par with R. Crumb, and if you knew me, you’d know that’s extremely high praise.
The whole “slice of life” approach to comics is passe to some folks precisely because so many other artists explicitly imitated Pekar, among a couple of others.