A great video. I like your explanations. Spot on about the colour; lack of contrast and greens are not easy to print well. I think I might unpack why the logo isn't iconic in another post - there's a lot of technical designer reaons why. But, you get the main points; it turns to mush when it's tiny and it's hard to interpret visually.
I don't agree with your third point. Yes, a good brand has a fixed colour scheme, but a logo has to often fit in (and stand out) with other logos and inside other (not Steemit) designs. For that reaons you supply variants so that the logo doesn't either end up sticking out awkwardly or some random designer doesn't take it upon themselves to create a variant anyway. An example of this is the social media icons on the voting line at the end of your steemit post; all of those logos are still easily recognised even though they are white/dark grey and don't have their original colours.