Back in the "Boss Radio" heyday of KHJ/Los Angeles, though the "playlist" of songs was selected, and playable oldies titles were in a book, the jocks did get to pick the songs from those lists that they would play. It was expected that they would balance slow to fast, rock to R & B and play the proper number of top songs/currents/hitbounds/and golds each hour as determined by the Drake format.
Did it work? Generally speaking...yes. BUT...the amount of time Ron Jacobs spent "riding herd" on the air staff, memo after memo complaining about DJ's playing the same song within 30 minutes because they didn't fill out the paperwork properly, poor song balance, mistakes in song selection and placement in the hour...was extensive. Don't believe me? Read the memos Jacobs has published.
Now ask yourself: does a modern day PD have the kind of time these very successful veteran programmers had to "ride herd" on jock performance? When a PD controls 3,5,8 or more stations, I think you'd be looking at a herculean task that certainly borders on the impossible. And don't say, "that's their job"...it's an easy thing to say, it's much more difficult to put into practice in today's consolidated radio world. They were 2 different worlds, then and now.
Why did most of the "free form" AOR's die? Because someone came in with a tighter, more focused playlist that eliminated the bad song selections that were made from individual DJ "biases" (read: "I like this song, so I'm going to play it").
Now, are there jocks who have that kind of "ear" to pick good songs to play? I'm sure there are. But, I would suggest that for every one that does, there's dozens, if not hundreds who don't. And that is really where the issue is...finding the jocks that have that kind of talent to create such a station.
Then, find a PD who is given the time to nurture such talent and stay on top of them to help both create the atmosphere to allow that creativity, while still keeping the talent from "falling off the cliff" when their creativity begins to interfere with their good judgement.
Now, find an ownership and management willing to take that risk in markets where there are two or three times the available radio signals that there were between 1960 and 1975.
Good luck.