I think what you are trying to say here and I completely agree is that because you study Martial Arts it doesn't mean you will always escape serious injury in a fight. Also there is a distinction between Martial Arts and Self Defence. Whilst any Martial Art training can only be a good thing, except in one respect you can carry injuries from practising the very sport you are hoping will help you in a fight.

Obviously your speed, reactions, strength are all going to be improved by studying a Martial Art, but take Judo which I did for a number of years, that is not the same environment as a Street fight, no Judogi to hold, no soft mats to land on etc. There are better Martial Arts for Self defence, I would say MMA is probably the best for this.

Not everyone does Martial Arts for the self defence aspect though, some because of the competition aspect, some for the fitness (injuries not counting). I do consider the injury aspect a problem if you are relying on the Martial Art for self defence, in the later years of my Judo career I was it seemed always carrying some kind of knock and sometimes serious enough that I could in no way defend myself in a fight!