Mass orchestras were around in the 20s but largely didn’t turn jazz into blended commercial pap until into the 30s. To me, it lost its charm and appeal when it became swing. Those living and dancing during that era might disagree.
Music only rediscovered its raw charm again in the late 40s and 50s, losing it again in the late 60s. The 70s were experimental, the 80s largely bland, grim pap, the early 90s saw some interesting things happen, that was end of good popular music as we knew it.
From Charles, ta: