Didn't really say it was new.
I know you didn't, Dave. But I don't remember the echo effect used in Paperback Writer being "controversial" in any way. We were used to early tape delays going back to the 1950s. Sun Records mixed several Elvis Presley songs with delay like...
Analog tape delay was used for George Harrison's...
Recording The Beatles gets into this in detail.
What I remember most about the echo effect in Paperback Writer was that it was similar to another song which was recorded and released around the same time...
