The biggest headcount of a company I've worked in tech with is 60, most of whom were not in IT. The other tech companies are all 10-20 people, including part-timers. Only one company I worked for sold to Fortune 500 - ironically this one had the shabbiest dress of all.

Three of those companies had lawyers - they all dressed in suit-with-optional-tie. As did their visitors (visitors rarely optioned out of the tie) and the lawyers I'd talk to from other companies (admittedly a rare occurrence). Apart from the medical sales at the waterfall place and finance staff, I rarely see a suit jacket in the neat casual dress of other staff (IT or otherwise).

I realise this is all anecdata, but at the same time, the 'neckbeard and t-shirt' idiom is a grossly incorrect stereotype.