I'd like to include Sabbath, but their first album wasn't released until February 1970. The first Yes album was released in 1969, but I didn't care for it. They really hit their groove in 1971. Ahhh, The Hollies were quite good until Graham Nash left. Alice Cooper also released one album in 1969. It wasn't all that great. Personally, I think "Killer" from 1971 was his first really good record.
Why would any of those people fix themselves when they don't think anything is wrong? Most of this lot tend to blame others for their failings and woes.
RE: Significant event
And that's still how I like'em...