They are correct, this accent was a thing:

And no, it’s not the same as the mid-Atlantic accent common from the 1920s to the 1950s. I’m guessing what mostly killed it off is that it started to become less of a stigma to have a regional accent, and sometimes accents shift for no reason at all.

But that accent is now mostly gone. Don’t believe it exists, watch talk shows and commercials from the 1980s. You’ll see. It’s bleedin’ obvious.