I don't get this attitude. Really and truly don't. It was a "perk" for what, a year, with offsite guests being a part of FP+ for only 4ish months. It was not an onsite perk, it was a stage in a roll out. For many of us it's been crystal clear that the day of only for offsite guests was temporary.
Disney never portrayed the ability to prebook as an onsite only perk, and it would make no sense at all for them to make it so. I don't get why you're acting as if onsite and offsite are now equal in all aspects because Disney gave something to offsite guests that was never part of the perks of onsite. Makes no sense to me. Did onsite have no perks a year or so ago before FP+ existed?