What I was arguing against is the maximizing impulse on the _other_ end: the notion that it's so self-evidently universally valuable that the primary reason to not dress well would be Virtue signaling.
That comment you linked to is just flat bullshit. People who desperately try to justify strict old-fashioned dress codes somehow conflate "you can literally lose your job if you don't dress this way" with "I feel awkward being the only person dressed this way, even in the absence of anyone else's reaction". It's insane to me that so many people uncritically parrot this utter nonsense.
There is also big difference between formal rules you can be fired for not following and informal ones - informal are still limiting but people cross them once in a while and you often finds it is actually ok in the long term.
People like to generalize tech as if everything would be stereotypical frat like start up, but it is not the case.
I personally find psychological benefits to dressing nicely -- I feel much more industrious and "ready-to-work" when I wear a nice outfit to work compared to tshirt/jeans/sneakers, plus I get a nice "switch" effect when I get home and can take it all off. Similarly, I feel more prepared to exercise when I switch into my exercise clothes, even though those DO have "real" benefits thanks to their cut and material.
Beyond that, the signaling can be extensive. Not all signals are "quality" -- you can dress to show off your creativity or as a means of expression (I personally love to thrift/vintage shop and learn about fashion trends from other eras). You can dress to emphasize/de-emphasize various aspects of your face and body, presumably for sex appeal. And sure, you can dress to show that you've got money to spend.
But a lot of times, people dress to fit in. This can apparently get venomous in certain professions (finance, for one). In tech, there's often a dress code, as described in this comment[1], and "dressing like you don't understand why people care about nice clothing" is realistically pretty close to it.
1: https://news.ycombinator.com/item?id=14404413