A healthy, well-proportioned human form looks nice to most of us basically at a genetic level. The whole point of good fit is to further accentuate/bring out that form. Saying fit is way less important than shape makes no sense, they go completely hand-in-hand. And 'style' is completely subjective.

I clicked the link, then clicked media, most if not all of the images were of people who were “in shape.” Heck, there were even pictures of people at the gym. Do I need to dig deeper?

Being in shape means having better posture.

Having better posture means making better impressions.

Making better impressions is the whole purpose of dressing nice.

You don't have to be a macho with bulging biceps and a ripped six pack, but you can't be a fat couch potato made of blubber either.

You clipped the second half of this quote, "and buying clothes that fit well". That does seem to be a big part of what dieworkwear guy talks about.

You fell for the 'menswear' meme lol.