To quote Twik from another post, the one about the lady that wants the man to pay when she goes with him on vacation cause "that is what the man does", "you don't get to mix and match" traditions.
It has already been mentioned in this thread, but here it goes:
Column A: In older times, people would typically have a very inexpensive wedding in the backyard, have a social to help them get started in life, and that was it.
Column B: Nowadays, people have lavish weddings as a rule (as in, even if you are not rich, you still typically go into debt to throw the fanciest party you can possibly afford - that is what I mean by "lavish" here, not necessarily that everyone is having 8 ice sculptures or something like that). They also have registries with expensive items, bachelor and bachelorette parties paid for by their friends, and multiple showers.
It does seem to me that people that are having all of them are picking from both Columns, yes, and I would find them greedy.