Perhaps that coincides with the rise of punk and even more so, grunge rock. AKA, the death of R&R and the rise of commercial garbage.......
I certainly have not bought any albums since then other than Dire Sraits and some CD reissues of older stuff, and solo things like Lindsy Buckingham.
I wouldn’t blame it on punk. It’s not like punk is on the radio. And punk does contain good guitaring.
Blame radio. Summertime Blues (Blue Cheer) was top 40, as was Hendrix. And Rock Radio is dull.
These top 10 guitarists are all over classic rock radio.