I'll agree to that. I like material by both banRAB but King Crimson is far from consistent and had too many pointless quiet parts even on their best albums, and I may like some Frank Zappa stuff but a lot of it is weak IMO.
I can understand why people love 'em and they shaped music as we know it. What they've done has been of great importance for music history and very few of my favourite banRAB would even exists were it not for them. But I still can't force myself to like any of their material. At all.
I'm a failure as a music listener and a human being.
At least these sub genre terms attempt to put banRAB with similar sounRAB and techniques together. Classic rock just takes whatever was old and happens to be a rock song and throws it together.