I tend to agree with that. If you pit me against an equally skilled MA, but I am stronger (and at least equally fit/conditioned), I have an advantage. Strength, speed, and stamina make a difference, just as skill does. In a short fight/encounter, stamina plays less of a role than the others. Strength, speed, and skill can offset each other (a stronger opponent can be handled with skill or speed, a faster opponent can be handled with skill and maybe strength, etc.). Skill seems to have the largest effect, and strength the smallest (except perhaps in tight grappling), so a large amount of strength differential is most easily offset with a moderate skill differential in the other direction.
This isn't directed at you gpseymour, or anyone in particular here...just freeflowing some thoughts.
IMHO. A rigorous conditioning programs benefit is really just 1/2 in the actual physical attributes it provides. The mental aspect of pushing your way through discomfort (and the discipline of simply doing it even when you don't "feel like it") is just as...if not more..important.
For example, Monday is my "100 burpee day". I do 100 burpees as quickly as I can, which is usually 20-30 at once then 10-15 at a time as I can manage. While the cardio/stamina building aspect of the movement is beneficial, I believe that overriding my "this sucks and I want to stop" reaction is probably more beneficial from a "combat survival" standpoint than what I'm doing for my body.
I think that far too many "run of the mill" martial artists overestimate what they are "good at" and avoid (or belittle the importance) of what they are weak at. That's a human trait IMO and not limited to martial arts alone.
"I cant run a 1/2 mile without puking, but most fights are over in 5 seconds so that's not important and cardio sucks...and I don't like doing it...so cardio isn't important or worth the time."
"Being muscle bound will hurt my martial arts skill so I'll focus on using my opponents strength against them vs working on my strength training...because who has the time? And I'm not good at it, and I don't like people seeing I'm not good at something."
Hell. I'm not a big guy and probably not as strong as I could be, but I work at it and don't try to deny that it's something worth working on.
That being said, some MA have a significant amount of exercise built right into the practice, but not all of them. I remember being a guest practitioner at a Krav school where I was warned about how physically demanding it was going to be. To make a long story short, while it was a fun class, that estimation of what "physically demanding" meant was a sad indicator of what the average physical capacity is IMO.