It may become much more common soon. Just check Google on "Pennsylvania filial responsibility laws" and one finds a number of law firms suddenly weighing in on the topic "Poor laws", making children and sometimes siblings responsible for parents debts are on the books in 30 states, which may get more aggressive with them given longevity and economic pressures, and even some nursing homes may go after family members directly, without waiting for Medicaid.
This is not about just emotions. Filial responsibility can come about regardless of a person's "choices". It could turn around our concept of personal responsibility.
With parents having longer lifespans and possibly longer periods of disability because of medical advances (which can have two faces), previously childless adults are sometimes forced to deal with becoming "parents in reverse". There can be legal implications. Responsibility for an incapacitated parents can be enforced by Adult Protective Services in many states and has legal (sometimes criminal) implication sometimes similar to those for minor children.
As for "LGBT people", it does seem that the age off "separation", and living our own lives as if we were on another planet (a mentality common in the 70s when I came of age) is long over. It makes the capability to get and stay married (in an emotionally permanent relationship) and participate in raising another generation and caring for a previous one (and having some command over a family structure) a likely prerequisite for "equality". And the moral arguments about "commitment" make us run in circles.