This belief is why so many people are complaining about the site. Put simply I (and I assume others) do not believe that you understand matrix multiplication as a result of this site.
We could be wrong. Please explain matrix multiplication.
I don't think that makes the site worthless or worthy of the some of the scorn I'm seeing in here.
I strongly agree with the complaint that "this completely misses the point" is super negative and dismissive and should be condemned.
If we-the-community want people to keep making things for fun or to try to help people, we have to criticize them graciously instead of saying that they are so wrong as to be useless. Not because it is moral or proper to do so, but because in practice dismissive and scornful negative feedback makes creators less likely to create new things or to try to improve old ones, and that's bad.
I think your core fallacy is that all people need to be taught in the same way, and that there is one correct way to teach people. The videos you link to may work for some people, but not for others. This explanation may work for some people, but not others. It turns out not everything works for all people.