@Xitel Honestly, I feel like you're right. A lot of fashion choices aren't practical for everyone, and sometimes they aren't practical in general. Dressing to stand out as opposed to dressing to be comfortable and look good by most peoples' standards are different, and I feel like this manga and MB's advice are basically just opinions when you get down to it.
The best rule of fashion is just to do what works for you and your environment, and the most important adage to remember (imo) is "No shoes, no shirt, no service." with the caveat that those signs also assume you're already wearing bottoms like pants.
Plus, depending on where you live, dressing to be nondescript and blend in may be the safest thing to do. Making yourself stand out might make you a target of theft or violence, especially if you live in an area where there are a lot of prejudices, and you're a minority. And despite stereotypes to the contrary, anyone can be a minority, you just have to go live in a place where people like you are a small proportion of the population.