A couple of points:
1.) I think this is a terrific, important, useful thread. We absolutely NEED to be discussing horse welfare, how training is perceived by the non-riding public and what does and does not constitute good training, training by force and abuse. Please, please, let’s not make it personal and keep to the very important topic .
2.) Anyone on this thread who can truly say they have never resorted to training by force, never over-disciplined out of frustration or acted out of temper handling a horse, please stop following/contributing the thread. Even if you exist, this conversation isn’t really about you.
We are all imperfect horsepeople. Some of us have been on a lifelong journey, doing better once we know better, trying to do better by our horses, trying to learn more. I count myself in that group, BUT (here’s a big, fat, hairy BUT…)
I came up riding school horses at backyardigan kinda lesson barns, and then a kinda fancy show barn, and all I was EVER taught was that if a horse didn’t want to do something, it was your job to MAKE them. So I got good at that. 
As a teen, I didn’t even realize that not all horses had been trained to jump, and jump courses, and when I encountered a horse that couldn’t/wouldn’t/didn’t understand what I was asking, I made the horse more frightened of me than jumping the fences, and when the horse jumped around, counted that as a success. So, sadly, did other people.
I was very fortunate that in my late teens, I met an instructor, trainer and mentor that had a system for training that involved small, incremental steps, not scaring the horse, building on what had been trained previously - and a barn full of happy, willing, obedient horses as proof that the method worked.
But even with that example, there were times I resorted to cruder methods and training by force. I am ashamed of that. (I never stood behind a student and whipped their horse over a fence, thank dog. But I certainly overused a stick on a stopper. Absolutely, I did. I can only be grateful there isn’t video. ) The ONLY thing I can hang my reputation on is that I kept learning and I kept trying to do better. If you were to draw a graph of the amount of force I used in training over the years, it would be a straight downward line ending at very close to zero. Because the more you know, and the more tools you have in your toolbox, the less likely you are to resort to force.
So the big question, the useful, productive question in this thread for me is, how the hell did this happen? How did Mark Todd, who has a bigger riding/training toolbox than I could ever dream of, get so frustrated that he resorted to this? And how do we give other, less famous, less successful riders and trainers enough tools so they don’t get to the bottom of their respective tool boxes?
PS - And if you’re still using the force based techniques you learned as a lesson kid years (decades? generations?) ago, stop. Learn and do better.