Yes I knew that was him (and he was in Spinal Tap).
Older folks not buying as many albums is a component of the sales slump but there are plenty of albums targeted to over 25 listeners. The industry releases the albums but radio doesn't play tht songs.
Classic rock plays the older artists but not the new recordings by the older artists. They also don't play the boxed sets of "also rans" from the eras that those listeners like.
Soundscan doesn't look at the indies as well (independent stores may not participate, it doesn't include their mailorder catalog sales, and since they don't get commercial radio airplay, their songs aren't tracked on playlists.
I posted another article about a month ago that said the independents are doing just fine.
There was a struggle in the music industry when that "rock and roll fad" came up. Dick Clark helped tame the wild artists and substitute poster idols but it came back in the 1960s. Frank Sinatra and others (primarily ASCAP artists) never held quite that reign on the charts again.
I've never been satisfied with the rock music I heard on the radio (starting with listening to radio as a kid in the 1970s, hated disco, Kiss (too gimicky), and fern bar music). I do listen to some music from the 1970s now (including IRS's The Cramps, WB-Sire's The Ramones, and some Australian garage punk) but even today it doesn't get radio airplay. Since I haven't looked to radio (or mainstream tv/movies) to validate my musical tastes I don't particularly notice that music product sucks today, more than ever. I listen to plenty of great new bands but the industry would rather have an unsigned act than an established indy band and would rather have performers under age 25.
Another thing that people don't take into consideration enough is that there is a music/entertainment GLUT. How many cassettes, LPs, and 45s do you have? Now then, you can trade some of those in at a store and get credit where you can get someone elses' used CDs and LPs. None of those sales help the "music industry" because they only take into account new album sales. Even new sales of Dark Side of the Moon no longer track under the revised ranking of Soundscan.
Consider too that a DVD of a movie can often be found for the same price (or less) than the CD soundtrack for that same film. It's a buyer's market but the music suppliers still think they can raise the price point for CDs.