John, this isn't directed at you, just at the premise of this discussion...
while I agree that every training method doesn't suit everyone, just blanket-rolling karate off and throwing it away isn't the answer to self defense training either. I've been doing karate training a long time, and also Judo, jujutsu, Aikido, and weapons... so I don't feel that any one art has "the answer". It depends on a lot of circumstances. Think of attacks as questions, and defenses as "answers".
Personal health is one of the considerations too. While I've had techniques that would work great anytime, my recent health issues with my hip and back have caused me to have those techniques unavailable any more... so what does that mean? It means I need a new answer to those "attack" questions, and a reasonable response based on my current situation.
In the 1980's, I had a spin kick that would take down an elephant... but those same problems take that option away, so I have to have another answer. Is it in karate?.. maybe. Is it in jujutsu? Aikido? Judo? weapons?... just where do I go to "replace" that technique? The answer is that I go to "scenario training" and "work it out", using the techniques that I have available in my "toolbox".
Fighting is fighting... and the guy with the best tools usually wins. If he chooses poorly, he gets beat. If he doesn't have the tool, he loses. It isn't rocket science to understand that "not all training fits all situations", and even the invincible get their a$$es kicked when they don't have the answer at the time of attack. That doesn't negate anybody's art, just their application of it.
I watch all martial arts with a critical eye, and an analytical one... to see if what they advertise is actually what they deliver. The current craze is MMA, which is a "piece of this and a part of that" combined to create a fight for television. While the "crowd" thinks all these guys are invincible, they wouldn't last long in a lot of arenas where the questions to them are different and their responses had to be different. Punching techniques are one good example... it doesn't take much skill to sit on somebody's chest and frail the hell out of their head... while getting that position might take some grappling skills, the pummeling of somebody you have pinned down isn't really a skill... it's a "technique of opportunity" where almost any mechanics will work and while there's a referee there to stop the match, the damage is limited to the good judgement of the referee... which doesn't prove the "viability of any art" to me.
You have to understand fighting to understand the viability of an art. If it's "contest fighting", it's one thing... if it's "fighting for your life", it's entirely another. Do you use the technique to create an armlock, or to break the elbow and destroy their weapon?.. so the lengths to which technique is allowed to go also has a lot to do with how effective it is. How that art blends into other arts also is a consideration to how effective it is.
It's easy to start bashing other arts and talking about their weaknesses, while not acknowledging the weaknesses of your own. Those are a matter of training, training methods, and how you actually practice (real or scenario) and how "alive" that training is allowed to go. Is it "contest alive" or "real life alive"?
I've read a lot of "bashing" on these boards, usually expressed by someone training in another art that's just parroting what they hear in their gym or dojo. The most of the time, it's by "newbies" that know just enough to get killed in a fight, and need to show their bravado . Their attitude changes when they run into one of those 900 psi lunge punches from a karate master, or one of those 2200 psi roundhouse kicks.
It takes years to learn and understand fighting. While younger people have the ability and flexibility to do some amazing things, they don't necessarily have what it takes to win in the real world. The old saying "old age and treachery will defeat youth and skill" is more true than you'd want to admit. I've seen too many of the "deer in the lights looks" from youngsters that really thought they "had it" when they fought one of the older guys with a bigger toolbox of techniques. I've even done techniques on people who practiced the same technique, but didn't do it as well as I did, and see their eyes opened when they found out what could be involved in it.
Which arts are useless and which ones are not are just discussions. The real answers are found out on the floor and in the scenario where "all options are available" and winning and losing are a matter of who can walk away.