lol, yes, well I'll have a go with MMA (seems fair, I started this)
MMA is geared towards a specific goal, and that is one one one fighting against an opponent of roughly the same skill level. Things outside of that window are generally ignored. Some of them can be trained within the same framework, Multiple opponenets can be done, stick fighting can be done. But it is still confined to the trained opponents who know they are in a fight model. Not to mention those things are a rarity, if ever for most people. But at the same time I would probably consider the Dog Brothers methods MMA, or a variant of it, and they are very heavily into sticks
So generally MMA lacks in weapons and multiple opponents.
It does take surroundings into consideration to a limit degree, in that you have to be aware of walls / cage / ropes, depending on your training environment, and those things are a part of the strategy. However other people are generally ignored and you can get a sense of tunnel vision in that you train always just to worry about one guy.
The other thing it lacks is training geared towards situations which are not fights. MMA, as everyone has heard countless times, is all about live training, against resisting uncooperative opponents. However in "real life" that is not always what you get. SOme situations may be more static, sometimes you can use physical force or control, without escalating things to a fight, which is what MMA is geared too. Sometimes that wrist lock, or comealong is all that is needed to subdue someone being a jerk, but not to the point where a full out fight is going to happen, yet something is needed to get them to cease being such a jerk.
One other thing that I think could get people into trouble with MMA is that there is a different end game. In sport fighting when you sense weakness or that the other guy is rocked, you go in to finish, and you keep going until the ref tells you to stop. In the real world this could be called "excessive force". Once you are mounted on a guy pounding his face in it becomes harder to call it self defence.
Finally (of the top of my head) gloves let people hit harder, they protect the hands. And any gloved sport athlete can fall victim to a broken hand if the adrenhaline kicks in and you start blasting on someones skull.
Oddly enough the weaknesses in MMA come from what I would call its greatest strength, the training methods. Assume a skilled opponent, and use as few rules as you can safely use. That is MMA, it's what makes it great. That everything is tested, tried and everyone gets a little beat up and goes home happy. But, not everything can be fit into that model. Not everything should.Trying to do everything would leave us all with no real skills in anything.
In a one-on-one unarmed fight with no outside interferance, all other things being equal, I give the fight to the MMA guy everytime. But that is not the only way force gets used, not by a long shoot.
I think sometimes MMA practitioners get cocky about that though, too much competitive spirit, or testosterone or whatever. But as a whole we often judge everything to our standards, and of course everything else falls short. Just as MMA falls short under different sets of standards.