Is it normal that i dont understand why someone would have to pay alimony?

Whats the point of alimony in this day and age? It was given exclusively to women upon its onset in a day when women almost never remarried after divorce. Most women do remarry these days.

Where i live, alimony has been practically abolished, but there are some states that still give exes a good chunk of a guys (sometimes womans) paycheck to their ex. Even when they were living with another man and had only been married for less than a year. What gives? Its like the law says you have to pay your ex to screw someone else. Am i the only one who sees this as ludicrous?