Vexillology

I got about twenty minutes into this before giving up, and it seemed... well it seemed a lot like he had started with the position that he liked those flags and worked backwards from there. It's fine if he likes them, obviously, but the justifications were very flimsy. Like when he grumbles about the "flags should be simple" guideline having no reasoning or explanation literally immediately after showing a slide with the reasoning for it

In practice, it's not reasonable for a flag's identification to depend entirely on it being the only one with two little horses in the middle. If it's an actual physical flag on a pole and not a printed graphic, we very often cannot make those horses out

The escutcheons on the German state flags could still be incorporated in a design that isn't just the German flag with said escutcheon on it. Look at the flag of Zeeland just across the border in the Netherlands, for example - 16th century escutcheon in the middle, but entirely recognisable even if you can't see the middle at all. It even draws the field from that escutcheon

The NAVA booklet doesn’t present itself as rules for evaluating flags, it's guidelines for designing new flags. They are the advice of Kaye and his fellow vexillologists, and they're perfectly clear about being advice that is okay to not follow

I do think it's pretty sensible to criticise a flag for not being easily identifiable as that specific flag. That's the primary purpose of a flag. Failing at that is not ideal