Some of it. But when comparing formats, don't look at what they play... look at what they do not play..
No, it has become more fragmented, with extremely polarized subsets of the followers of that format.
Again, look at what they don't play both by style and age-group appeal.
You are forgetting all the other formats, from R&B/Urban to Country to all the Hispanic formats.
You are also forgetting that back in the later 50's and earlier 60's, we had, in most markets these formats: MOR, Top 40, Country and R&B. In what was then a top 10 market, Cleveland, we had 3 MOR stations, 3 Top 40's and two R&B stations in that era. That's it.
So if you are looking at format variety, we have vastly more variants today than ever even if we don't look beyond the AM and FM alternatives.
Another example: in 1960, Traverse City, Michigan, had one AM station with 250 watts. Today, there are over 25 stations that put a "local" signal into that city, and countless others that have marginal signals. Every sustainable format... and then some... is offered.