Read the last thread until it died.
Heres 3 points i think is important to consider from my own experiences, I wont mention any names.
1.
Coaching is good for getting better players, with or without coach, they will have to step up their game.
Example: I was playing a spacieplayer (dont sure exacly who, playing Ice Climbers) which were no real trouble since I could allways rely on a certain chaingrab, getting the % needed to KO.
After a few times repeated(not as many KOs) someone in the crowd() shouted how to escape the chain, which I heard and used the info the opponent got to get an early kill instead.
Next time though the opponent learned to escape, when the early kill wouldn't work anyway, and I think even though I got the lead that set I lost atleast one match(or even set, not sure since I've been on alot of tournaments since then :/) due to the fact that the crowd did this for my opponent. Also alot more players has since then adapted to that situation, which is in no way a bad thing since it forces me to find useful mixups and cannot be able to rely on the same thing over and over again.
Having to work around that has forced me to take time to practice, getting better at the matchup so when I face an opponent who has done their homework it'll definitly pay off going that "extra, but without the advice, uneccecary mile in just that situation".
2.
Like someone probably should have mentioned earlier, it's really hard to create a rule that takes coaching/communication away from player to player, or crowd to player(including hints, codewords, just pure advices or added rps games(shouted techguesses)).
3. IF such rule by some way could get a good and enforceable(like the "stalling rule" has been enforced ever), the sollution probably would require that the players would in some way needs to get their matches isolated in "small rooms" or anything.
Which atleast now seems like something theres not enough resources for. But may be doable in the future.
EDIT: I'll get convinced that it should be banned when Mango coaches Armadas Fox to beat Hungrybox in a set.