Well, helping the children purchase a home is not all that uncommon.
Before the days of easy credit and no income check mortgages (now gone, thank goodness), persons had/have to put up 15% or more for a home. Not many youngsters then or now have that kind of dough lying around.
In parts of the NYC area, a simple starter home starts at around 350K, and that isn't even in some of the best areas, and or for a really great home. At those prices, you are looking at over 50K upfront money, just for the down payment. This does not include closing costs and the rest of the cash outlay for moving into a new home. So unless one has been very careful all one's rather young life,and or has been lucky in finances, mummy and daddy, and perhaps the grandparents are going to have to chip in.
IMHO far better to give a newlywed couple funds towards their first home, than tons of silly wedding gifts that will either go unused or are not required.