No, it's not even about sex, it's about benefits. It's a great deal: find one person with government benefits, and have 3 or 4 "marry" him or her - then you can have several adults enjoying one person's benefit package. And what's to stop them?
“funds attached” persons who are minors, disabled, etc.
have always been at risk. this just publicizes it. (BTW
the “funds” need not be public benefits, but the vast
majority are)