Personal tastes and preferences and opinions aside, clothing is a pretty important aspect of communicating. Easy reference point is Mean Girls: On Wednesdays, we wear pink. In that scenario its simply a means of communicating conformity and support for the group. Seasonal tastes change because tastemakers set them, and people who want to be in the zeitgeist follow suit.

And even in sub-cultures where one is just trying to communicate their distaste in fashion, there are usually unofficial dress codes. At nerdier conventions I typically see screen t-shirts riddled with pop culture references, or standard issue polos + khakis that communicate a sort of "I'm professional and I don't want to overthink my wardrobe". They're also the only place I see utility kilts, which definitely communicates something.

Einstein famously had several copies of the same outfit, because he didn't want to think about dressing, but he found one that worked for him. And I've seen several engineers copy this approach - communicating efficiency and I'd argue at least some desire to emulate an Einstein.