Fashion is a code you use to send subliminal messages about yourself. We live in a superficial world, and humans have primal urges to quickly judge people based on their looks and clothes.
If you dress "well", you will attract the attention of other well-dressed people, and they will feel a natural inclination that you are one of them.
This may or may not be desired, but it doesn't have anything to do with "self expression" or "advertisers".
Autists like yourself are legendarily unable to fit in with society. You can't mimic other people's emotional responses, you can't figure out how to match hues and shades of colors, you can never see the difference between a suit from Armani and a suit from Target.
People who rely on cues like this, such as sales, politics, entertainment, management, they all have a better grasp of how to dress to make it easier for them to get what they want.
So if you want to wear some dopey ass shit, be my guest. It makes my life easier, because no one with power will take you seriously.
I always dress as well as my superiors, if only to demonstrate to them that I have that skill. And it is definitely a "skill". If you think you can just buy an expensive suit and you'll be able to pass as normal, that won't work. You need the shirt, the tie, the belt, the shoes, the watch, the haircut, the cufflinks, the pocket square, the briefcase. And you need it day after day.
Or casual days, you need top notch casual clothes. When your boss accidentally runs into you off site, you have to look sharp then too.
Again, this is all a type of language that higher level people use to display their social and business proficiency.
The fact that you can't do it doesn't mean that it isn't a valuable skill. It's like your bitching that you can't play the piano.
tl;dr OP is a fag.