Point is flying right over your head. Current, updated, slang usage does not address your patently incorrect assertion that it never refered to the baby boomer generation. It became a pejorative as part of referring exactly to that generation and then was expanded and generalized to older people. Exactly the same way Millennial commentary started out pointed at exactly that generation and then became generalized to a rolling window of "those young people". Even though the actual millennials are in their early 40s and late 30s now.