No, the fact was that there was no research for those station's playlist and, in total truth, the songs were often smoke roasted in the studio. When Lee Abrams created his hit based album rock format in the earlier 70's almost all those free-form rockers faded away. A few, with very talented staff members in the bigger markets, survived a while longer.
And even then, the handwriting was on the wall. Since mi amigo David brought up "bigger markets" let's look at the one he and I (and
@michael hagerty as well) know extremely well ... Los Angeles.
94.7 KMET was one of the pioneering "free form" progressive rock stations, adopting the format in 1968 when Tom Donahue moved it from crosstown 106.7/KPPC-FM.
That same year, 95.5/KABC-FM, forced to comply with new non-duplication rules, split from 790/KABC and tried doing all-news (which lasted a few days longer than three months; they dropped it the same day 980/KFWB went to that format). They then created an automated progressive rock format called "Love", voicetracked by the late "Brother" John Rydgren, which also ran on their FMs in New York City, Chicago, San Francisco, Detroit and Pittsburgh, and that was also when they started broadcasting in stereo. "Love" was something of a disaster, if reports in the trades are any indication, and they went live and free form before long.
In 1971, Tom Yates replaced the KABC-FM progressive format with "Rock'n Stereo KLOS", which Wikipedia accurately --

-- describes as "only the top tracks from the best-selling rock albums". This is generally considered to be the first AOR (album oriented rock) in the U.S., and also is thought to be where Lee Abrams got his inspiration.
It only took them a year to be the highest-rated FM rock station in the market, and it was mostly downhill for KMET by then; in reality, what audience they had initially as the only rocker in town mostly moved to 95.5 when Yates tightened the format. I remain amazed that 94.7 lasted until the beginning of 1987 before finally collapsing.
So, even back then, the listeners wanted structure and familiarity to rock radio. The only difference between KLOS and the top-40/CHR stations over the years (KHJ, KKDJ, KKHR, KIIS-FM, etc.) was -- and still is -- no jingles and no high-energy jock talk-ups to the post.
This example alone should disprove the fallacy of "outside the box" programming being a ratings success.