I absolutely agree. All these Boomer, Joneser, Gen X generalizations annoy the heck out of me. Studying demographic cohorts is important, and a range of verifiable data can be ascertained, eg, educational degrees, income, marriages and divorces, etc. But it’s laughable to apply vague labels — greatest, dumbest — to large groups of people just because they share a range of birth dates.
It must be understood as pertaining to a bell curve within each population group. I’m neither Greatest Generation nor Boomer, but the former are my heroes and heroines, my striven-for ideal. So I’m living Gen-X proof of your point, though your point assumes understanding the labels in too strict a sense (i.e. EVERY SINGLE PERSON in group x behaves y.)