I can't tell you how often this ends old people's lives. They start to aspirate food, get hospitalized for nasty pneumonia because of it, we try to feed them pureed food (essentially baby food all over again) and thicken their drinks, they struggle to stay hydrated and nourished because of it, they aspirate and end up in the hospital again. Rinse, repeat.
Oh, so it's yet another one of those problems caused by that whole "let's take this four legged mammal body plan and make it stand upright" thing. Thanks, evolution!