Well that usually means "I haven't listened to any of his stuff beyond the early 70s"
He's put out some crap but he's also put out some incredibly good albums such as Tonights the Night, Zuma, Comes a Time, Rust Never Sleeps, Weld, Harvest Moon, Ragged Gory, Freedom, Living with War, Chrome Dreams II and the just released Psychedelic Pill.
But yeah! Other than alllll of those classic, beloved albums, and probably several more, everything since the early 70s has been awful.