Wait. What’s the obvious reason? Cigarette ads?
That probably knocks out much of the first few years or so, but there were a number of episodes GSN aired from ~1955-56 that didn't have such sponsorship.
Based on what GSN's aired, if any show in the archive is unlikely to show up on Buzzr due to cigarette ads, it's
Judge For Yourself... and that's not even getting into the potential issue of music and performer rights.
How much Feud has aired? I don’t remember how deep they got into the Combs run, and the current series doesn’t seem to have aired very much either.
I'm pretty sure they've never had
Challenge or the 1994-95 season on the regular schedule.