Correct. My issue is just how some folks want *everything* from G4 to come back. The other major example beyond the "rule of six" on my mind is bringing back other species. We've got dragons coming back (at least in the toys), and I'm sure more species will appear in animation as time goes on, but bringing back the myriad species of FIM and/or fleshing them out further as many want could compromise storytelling IMO.
As long as they aren't assholes about it (which again is rare), folks can do whatever they want with fan content.
EDIT: By the way, good comic recommendation. Thanks for that.