No matter how long ago someone was taught, if they were taught wrong, and no one explained to them what was wrong, and they don't think it through for themselves, they do it wrong for the rest of their career.
There is no certification process for skate sharpeners - or for that matter skate techs in general. There really are, as hard as this is to believe, shops where skate sharpeners are taught how to sharpen in an hour or two, sometimes by someone who was taught the same way, and then allowed to sharpen customers' blades.
Also, it sometimes happens that if you have a person who isn't very expert sharpen a warped blade, and doesn't have the right blade holder to straighten it, the edge ends up longer on one side on part of the blade, and the other side on another. It's a bit hard for me to interpret this image from your video, but maybe it is warped. Most usually, it is longer on side at the ends, and longer on the other in the middle, which does not match what your video shows - but nonetheless, if a person doesn't have the requisite skill and intelligence, such a wrap could cause a problem for them. (But in your video, I would guess the sharpener didn't center the blade the same on the two ends, for whatever reason.)
And sometimes "professionals" are asked by their bosses to work too quickly to do a good job.
This blade could at least be fixed, with only a little metal wasted. We have seen others in these forums where the toe pick and tail were ground off, which is basically unfixable. On some hockey websites, you can see hockey blades that were totally messed up too - again by professionals.
Professional just means you are paid. It doesn't mean you are competent.
I had the underbody of a vehicle severe damaged by a "professional" mechanic, who lifted in the wrong spot. It developed exhaust leaks, and a gas leaks that almost caused it to catch fire or explode.
As a professional computer programmer, I was sometimes asked to analyze and fix other peoples' code that had incredibly bad mistakes, and that was also written in a very difficult to understand (poorly organized and undocumented) manner.
I'm sure that some of you have had "professionals" in other fields mess up stuff too. It's just the way some people are.