This is a maddeningly vague statement. It sounds like something I'm supposed to agree with, but without at least one concrete example, it could be total bullshit and still sound wise.
Another thing: by creating a strong impression of seriousness, jacket-and-tie creates a false , narcissistic sense of self-worth that can limit the true drive to succeed and that's a sad, sad thing when it happens. It's just an appearance after all.
Taleb may have been referring to certain "conference-whores" [1] who dress up like geeks to fit into the crowd. Hopefully, in science and technology, actions matter more than words and dress up, and that's one of the reasons we like it.
[1]http://www.bothsidesofthetable.com/2010/10/13/be-careful-not...
What I've learned, the hard way, is that you have to spend a considerable amount of your work time deciding for other people how they perceive you, and this is a subtle art. If you don't manage your image actively, others will manage it for you. This is as true, if not moreso, in a startup than in a big company. At least the social status rules of large companies (as broken and antiquated as they may be) are documented. In a startup, you often have situations where there are 20 employees who all think they're the alpha dog.
Wearing a suit and tie is a very cheap, efficient way to manage other peoples' impressions of you. Sure, it's silly, but the reward-to-cost ratio is very high. It's a lot cheaper and better than, say, sticking around the office till 9:30 when you finished productive work 5 hours ago.
"Your business suit will probably cost about as much as a computer monitor. You only need it once in a blue moon, but when you need it you’ll be really, really, really glad that you have it. Take my word for it, if I wear everyday casual when I visit e.g. City Hall I get treated like a hapless awkward twenty-something, if I wear the suit I get treated like the CEO of a multinational company. I’m actually the awkward twenty-something CEO of a multinational company, but I get to pick which side to emphasize when I want favorable treatment from a bureaucrat." [1]
Now, obligatory suit-and-tie-wearing can certainly be seen as a form of workplace oppression, but the motivation to positively impress business associates is perfectly valid. On the flip side, dressing down and cursing like a sailor can also be a form of calculated personal branding that conveys the desired impression (confident, powerful outsider) to certain prospective clients in certain situations. [2]
The suit is, as one might imagine, armor.
I don't see these as bad things. Unlike real swords, ties aren't hurting anyone. But yes, they go a long way back. There's a lot of legacy, for sure.