except because it's ranked, it's likely just to cause more tension between the guilds. Remember all the blackmail and stuff that went on in the Canon one, and that time Natsu completely rekt everyone in Sabertooth?

If the games are to determine individual strength instead, there'd be a whole lot less of that kind of thing, and it would generally have the same effect as ranking the guild, because whichever guild the winner of the games is in would be considered the "strongest"