This video has been making the rounds on the internet. It shows a sport BJJ match where one of the competitors enters seated guard and his opponent refuses to engage and even mocks his opponent. Eventually he engages and is EASILY submitted by the BJJ exponent via seated guard.
Now, I've seen plenty of grapplers complain about this tactic, saying that it's "cheating" or "cowardly". However, within the rules of sport BJJ, it's completely legal, and frankly effective. In addition, the rules state that a grappler must engage or they will lose the match, which makes sense. You can't simply run away from your opponent because you don't want to engage their guard.
I don't know, the general attitude of disgust towards how sport BJJ operates is just funny to me. If you want to compete in a sport BJJ competition, you need to learn how to deal with sport BJJ rules. There is an argument that such tactics can water down the self defense portion, but many people who compete aren't doing it for SD purposes. They're doing it for sport. Anyway, I just wanted to bring this up for possible discussion, because I think it beings up the typical sport vs. traditional MA debate, and a style vs style debate because plenty of wrestlers and Judoka absolutely despise these tactics, but due to the lack of other forms of grappling competitions, active compete in BJJ competitions because they're more widespread.