Thats bizzare and disturbing.
If they're in monogamous, loving relationships, what difference does it make if they have some ceremony at the start of it?
You don't get married because you have to have some ceremony. You get married because you want to. You want to stand up in front of everybody and tell the world, "This is the person I want to spend the rest of my life with!"
That saying you’ve made a commitment to someone you love is all well and good, but if you’re not willing to yell about it from the tallest mountain top, how the hell good can it be?
It’s not about making the commitment, it’s about celebrating that commitment and wanting to share it with everyone. If you’re not willing to do that for each other, then maybe it's not worth keeping.
PS: I'm a bit drunk right now, so that might have been a bit over the top