It is of course a spectrum between no support and supporting a lavish lifestyle. Some parents may be able to let their child sleep on their couch, but cannot afford to rent a bigger home with an extra bedroom. Some parents may be able to afford the groceries, but (after the age of 21) not the health insurance for their child. Some parents may be able to support their child, but with significant financial difficulties that would put a strain on family finances, make their retirement plans nonviable, or pushes back their retirement date significantly; so the child would not dare take financial risks because while they would not go homeless, they will be putting an unreasonable burden on their parents, ...

So yes, if the family is reasonably well-off (owns their home, has savings and good income, have a margin of safety in their finances) you can depend on them as your safety net. If they are not, you cannot or cannot in good conscience.