They're referring to the fact that pretty much everyone in the comments defended why we still use QWERTY over any different keyboard.
Usually when people say "Big ____" they're referring to giant corportations pushing their agendas for profit against the wellbeing or benefit of society. In this instance, it's certainly being used in a tongue-in-cheek manner.
They're joking essentially that people who vehemently defend qwerty are perhaps a little brainwashed.
It is known that there are keyboard layouts which are more efficient and faster (qwerty came about as a means of preventing typewriter arms from hitting each other), but none have become mainstream because everyone's used to qwerty.
Contrary to popular belief, the QWERTY layout was not designed to slow the typist down,[2]: 162 but rather to speed up typing. Indeed, there is evidence that, aside from the issue of jamming, placing often-used keys farther apart increases typing speed, because it encourages alternation between the hands.[11]
A feature much less commented on than the order of the keys is that the keys do not form a rectangular grid, but rather each column slants diagonally. This is because of the mechanical linkages – each key is attached to a lever, and hence the offset prevents the levers from running into each other – and has been retained in most electronic keyboards.