Purgatory theories are a really lazy fan theory because it can apply to just about any show. Seinfeld is in purgatory because theres a laugh track, it's god and satan laughing at them because they will never go to heaven.

"Take This Ed and Shove It", the original finale, seems to imply that the series may just be stories being retold between the Eds in their old age. The weird stuff that happens may just be hyperbolic memories 'recorded' through the eyes of children.