Here's a counterexample to this assertion ^. :)
I'm older than the GenY + millenials demographics.
I was largely ignorant of the cable (and ota) channels which specialized in classic tv.
Up until about five years ago or so, the only "classic TV" shows I was aware of was stuff like Bonanza...
More generally, at times I wonder how many of Rolling Stone magazine's old timers are still in the writers/reporters pool.
Or have all the old timers left (or been fired), and/or become editors + managers where they don't do much writing anymore.
I rarely ever take stock in various "best of" lists. Especially in niches which are very subjective, with no precise objective criteria to determine the ordering.