As a counter example one of the best developers I've worked with wore a business suit/formal clothes regularly. But he was in his 40s and it felt appropriate with his demeanor - it didn't feel out of place at all despite the office being rather casual (I remember more than a few people wearing sweatpants around the office since they would cycle/run to work)
Oh, there are certainly exceptions to this, Gary Bernhardt (whom I highly respect for giving excellent talks) wears exactly the attire I'm describing.
But we all have implicit biases, and it wouldn't be my gut feeling to trust a person who does not present as 'one of my group' like this.. even though I'm aware of the bias.
