Yes, I've known a good few of these. The guy I buy organic nuts and stuff from - who turned me on to New Orleans jazz a few years ago, listens to nothing but that and swing bands; in his shop, which is nice. He has a little untidy pile of CDs and K7s there - perhaps 50-100, I never counted.
I have NEVER known anyone like this. And I DON'T need to get out more
MG
Many of the people I knew at college in the mid to late 1970s were like that. They listened to a lot of Yes, Jethro Tull, Jimi Hendrix, Jeff Beck, Emerson Lake & Palmer, Frank Zappa, Allman Brothers Band, and other popular rock groups of the time. They had hundreds of rock albums, and about 20--30 jazz albums, and that was the way they liked it. They also had about five reggae albums, ten classical albums, maybe 20 blues albums--they didn't mind dabbling just a little bit in other styles, but the rock music of the time was definitely what they were mostly interested in. They enjoyed the 1970s fusion groups like Mahavishnu Orchestra, Larry Coryell and the Eleventh House, Weather Report, because these fusion groups reminded them of the most instrumentally oriented rock groups. They did not want to venture into any acoustic mainstream jazz--except that they also thought that ECM was "all right to admit liking"--they had a few Keith Jarrett, Ralph Towner, Gary Burton and Chick Corea albums on ECM. A lot of it was cultural and generational with them--the fusion and ECM were "young people's music" in their minds. They could not identify with older mainstream jazz artists, and the avant garde did not interest them. To them, buying a Dexter Gordon album would have been like buying a Dean Martin album, just a hopelessly square, old fogey thing to do. They could not bring themselves to do it.
I have made contact with some of them online in recent years, and they seem to have the same musical collections and tastes as they did back then, or else they don't really care anymore about music at all.