In my career I have seen this sort of thing more than a few times. Sometimes I would get asked what I thought about it, the tax implications, etc., other times I was only made aware of it when they brought in their tax information. I was fortunate to have a lot of very well off clients, at least by my standards they were. My opinion, generally, is that if the child is old enough to be on their own, and wanting to buy a home, then they need to truly be on their own and do the whole deal themselves which is what I bet the parents did at their age. But time and time again, I saw the children in their mid 20s to early 30s buying a house far, far nicer than their parents had at that age and, more often than not, a nicer house than their parents currently lived in. And their children were able to do that because of the help they got from the parents. Often, substantial help.
Mostly, the parents had plenty of surplus funds and there was not a lot of risk of losing any money on the deal. Just not sure what sort of lesson is being taught when they take actions to "help" in a situation like this. But it was their business, not mine.