That's mainly true because we (now-a-days) treat anyone under 24 as an invalid, needing constant subsidization. In reality, the only people who need welfare are: actual cripples, young children, and the elderly.
Cutting off the gravy train to young adults would have zero systematic effect.
I think you may have misinterpreted the point the parent was making -- some of us have families where the elderly leave wealth to the next generation when they pass on.
Cutting off the gravy train to young adults would have zero systematic effect.