looked it up on Wiki, and I guess I'm wrong. Oldies as a radio format is basically 1955 (the birth of rock and roll) to the beginning of the singer-songwriter era (about 1970 or so).
I think the confusion is that there's also a radio format called "classic rock" which is focuses on rock from the 1970s (and bleeding out a bit in either direction to the 60s and 80s).
When I think of LZ or the Who, I think "classic rock." When I think of The Platters, I think "oldies."
In reality, the years overlap a bit, so early LZ could be technically put in either, and so could the Beatles.