Columbia was the home of large-ego'ed producers - as DRooney can explain better than I can, a multi-track session tape was just the raw material for a producer to do his 'magic'. Some of that magic was at the behest of the artist (such as LB)
who often wanted instrumental balances fixed when the LP master was produced. Funny that the golden age of analog recording in the 70s was actually in the UK, where EMI and Decca refused to be caught up in the American fascination with 24-track classical recording. And one more thing ... we are stuck with those mixes from the 70s, good or bad.