I'm generally against doing procedures that won't really add life to folks - especially weeks. Years, though? That's years. Folks can be frail yet able-minded and so on. It doesn't really matter to me if someone needs to have some assistance to live, regardless of age.
Triaging criteria already exist. It is really a shame that insurance companies and businessmen have their hands in it instead of doctors. But I don't mind these criteria: They are, in general, for emergency situations instead of, say, routine gall bladder surgery.
And the people triaging at insurance companies are doctors and pharmacists themselves. A doctor not employed by insurance companies is also a "businessman", considering they get paid more the more they treat. No one is exempt from conflicts of interest, but since US voters didn't want "death panels", they get to deal with prior authorizations.
It's the same function done by the NHS or government in any other country.
Depends who is paying for them. Voters certainly can take Medicare away, or implement a triaging criteria.