Such a rule could be abused in really bad ways. If you're losing by 5 points, kick the ball into your own goal -- you're now down 6 points and win by default.
Ultimate frisbee captains can, I believe, agree on any subset of rules before a game begins. The inclusion and use of dodgeballs on the field was one modification of note.
Another figured out that swimming upside-down under water was faster than back-stroking above the water. Alas, this innovation was banned. And so it goes.
Politics gets into it, as anyone who followed the UCI's wars with Graeme Obree would remember:
This would mean that a team attempting the "suicide" strategy from the outset would need to be much better in that paradigm than the other team. If we assume that the skills involved are similar, this would mean that they could probably win anyway using the normal rules. Adopting the strategy partway through the game -- say, when behind by three goals -- could be effective, but if the other team knows about this, they would keep the difference to only two goals.
It would result in either a heavy emphasis on defense, or a strategy of scoring one goal and then passing the ball around for the rest of the game.
Since different teams get the initial and half-time kick-offs, it boils down to which team is capable of scoring the most own-goals in the same (lengthy) amount of time. The second team has a huge advantage, because they win by scoring 4 less own-goals than the leading team.
Of course, I prefer Ultimate, where "SOTG" is part of the basic ethos and the game is played without referees. I don't play organized hockey and I'm in no hurry to introduce my kids to it. I've heard too many horror stories about parents and coaches who believe that winning is the only reason to play.
That doesn't mean 'win at all costs,' but it does mean you need to teach kids why a level playing field is important. I don't think a 5 point auto-win rule is the right way to do this.
Referrers are coming to Ultimate. It turns out than in practice, you need them in top games. There's too much room for abuse. Look at the recent College championship for an example. The winning team did it by calling 'cheap' fouls. SOTG is still valid with referees -- there are no punishments in ultimate for breaking the rules (except for offsides). Everyone is supposed to be playing without the intent of breaking the rules and that's the difference between ultimate and other sports right now.
Winning is important to you. But not to others. many of us find other reasons to train, to suffer, to strive, and to enjoy a unique camaraderie with our fellow players.
> The winning team did it by calling 'cheap' fouls.
In what sense did they "win?" Why stop at cheap calls, why not trash your opponent's sleeping bags so they can't sleep the night before the finals? How about trash talking them so that they're too upset to play their best? Maybe 'accidentally' stomp a downed player's throwing hand?
All of these things value the score above proving you are the best at anything except being able to limbo lower and lower under the minimum bar of civility. Such actions cheat everyone, including the people who 'won.' Now they'll never enjoy what you say you value, proving they are the best. Maybe they were the best, maybe they weren't. They'll never know.
Back to youth soccer.
In this particular case, we aren't even really talking about winning, we're talking about a rule that you aren't to win by more than five goals and a team choosing to score on their own net to "win." Honestly, if I took the field and someone did that, I would join you on a quiet walk and leave them to enjoy their "win" alone.
That is neither winning nor losing soccer, it's something from a parallel universe where all that matters are some little black marks on a white piece of paper that gets tacked up on a bulletin board somewhere.