KW, you mention the double Windsor knot. Presumably, someone invented it when the previous Windsor knot just wasn't big enough. The reason it was invented was to accentuate and flatter some man's physique. The evolution of nearly all "classic" clothing has to do with accentuating and flattering someone's physique. You can decide for yourself which is better- making a lot of people look pretty good or making a few people look REALLY good. Those two competing ideas bounce back and forth in cycles of nonconformity and conservatism. When people are feeling particularly individualistic, the trend is for people to select clothes that make themselves look good. Those same garments are less likely to make the great mass of people look good and when the mood switches towards group-oriented thinking, you see a predominant look that hides more flaws and flatters the less-than-perfect. There is a truism that every man looks good in a classic tuxedo. (Of course, what exactly a classic tuxedo is can be debated for weeks.) Not every man looks as good in, say, jeans and a tee shirt.

The evolutionary process of western clothing is not perfect- fashion and marketing intrude regularly, as do such out-of-orbit influences as the Baby Boom, where a particular segment of the population wrested control of fashion and refused to relinquish it at the end of "their turn" approximately 25 years later. Another example would be the prominence of a person whose wealth or influence is so great that their physical characteristics are imitated, despite conventional tastes which do not favor them.

Theoretically, people dress to attract mates. Men dress to exhibit their physical primacy and their wealth. Those who have more wealth may be able to display it in some less obvious way, just as those with more physical perfection may be able to be more casual about showing it off. Somewhere along the way, displaying wealth has come to include being able to have new clothes and the need to distinguish new clothes from old ones begat fashion.

SO, if you look like Brad Pitt or the young Sean Connery, you may be able to bend the rules. If you are Bill Gates you can do the same thing. Of course, there are places that looking really good or being really rich will not get you anywhere, as cited above. In those places, the rules are what you need.