drop bear
Sr. Grandmaster
Fitness should be a fundamental part of martial arts if you want to be good at them, sure, but most martial arts instructors don't or can't do a good job of helping people achieve it. Why should I waste my time and money doing calisthenics and mediocre body weight exercises for 20-30 minutes of every class that are only going to be indirectly beneficial for my art anyway. Especially when there are much better ways to use that time?
Let's take BJJ or grappling in general as an example. Rolling hard for an appropriate period of time is the most efficient way to develop endurance for grappling, anything else is a less direct way to try to inroad those metabolic pathways. I'm sure there are grappling specific drills that are a good second best. Skipping rope, doing calisthenics or running can be helpful for developing that endurance if it's done at the appropriate level of intensity but it's not as efficient as just doing the thing and you're only getting more skilled at skipping rope or whatever. Body weight exercises will develop strength to a point but they aren't nearly as efficient as weight training. These seem to be the sort of thing a lot of MA gyms do for fitness and it makes sense because they're easy to do with a room full of people. You can do that at home to maintain your fitness between classes but it's a poor use of time in class in my opinion.
Going further, I think it's most useful to focus on your weakest link, and if you can't roll hard for any length of time without getting totally winded then you need to spend more time rolling to condition yourself to it and work on developing the skills to grapple efficiently so as not to tire yourself out fast. I've provided strength training to a number of BJJ players ranging from white to black belt, mostly in the blue/purple range. The thing that stands out for me is that they are almost universally relatively weak if they haven't been doing strength training already and it's their weakest link by far by the time they've reached blue belt. Most body weight exercises aren't going to do a lot for them because they're strong enough that it takes a greater level of effort to significantly trigger an adaptive response. When they start lifting weights they universally tell me that it's a lot easier to submit people.
I know some MMA and BJJ gyms have weight lifting equipment but I'm not sure it's the majority. Even if it was, how many of the instructors are qualified and want to be strength coaches, how many students do they have time to do strength training with? Besides that, lifting weights isn't the best activity to combine in the same session with trying to learn a physical skill like BJJ. If you're going to have to come in on a separate day to do the weight lifting it probably makes more sense to do that somewhere else and not waste the space in your BJJ gym.
I care about this because I don't have much time to train in the evening when most of the MA classes take place. I don't want to waste it on things I can do when I've got openings in my schedule. I don't care if someone else is mistaken about this, what other people think has no impact on my training. I do care if instructors start including a lot of less relevant fitness instruction in their classes to meet the requirements of someone's check list.
I might get my fitness coach to handle this.