However such signalling is harder to pull off than it seems, and most who try do it poorly because they don’t realise that the casual aesthetic isn't just a lack of care. Steve Jobs famously eschewed the suit for jeans and mock turtleneck. But those weren’t really casual clothes, those mock turtlenecks were bespoke, tailored garments made by a revered Japanese fashion designer. That is a world apart from throwing on whatever brand of T-shirt happens to feel comfortable to the wearer.
Also, how much is there to customize in a turtleneck? Seems like the same signal as a very expensive suit, "I have a lot of money", nothing more.
You correctly interpreted the point I was making — Steve Jobs treated his casual look as seriously as others treat an expensive tailored suit. And the result means he's still signalling importance and success, without also signalling conformity and "old world" corporate vibes.