When Major League Soccer started play 21-years-ago they didn’t follow the rules that most of the rest of the world were using. One such example is that their clock counted down instead of up, to try and align themselves with other American sports instead of the rest of the world.
Starting in 2005, MLS adopted the rules from the International Football Association Board (IFAB). People often mistake FIFA as the governing body over the rules (err Laws) of the game. That said, FIFA represents half the voting members of IFAB, but they are separate institutions.
You are probably wondering why all of this matters.