That's a common adage, yet some of our most used technologies are created or maintained by committees - the Internet, web technologies, ECMAScript (enemy though it started out as a single person project), C++, OpenSSL, Unicode - these are all design-by-committee projects.

Regarding your point about democracy vs oligarchy, this is to some extent a spectrum. There are few truly democratic (one man one vote) organizations, that is quite true. But I still have much more of a say on how my city is run than my company.

And there are some examples of huge co-ops with a great degree of success. The biggest is the Mondragon corporation in Spain. They're by no means an example of a perfect democracy, but again - workers clearly have much more of a say there than in most similarly sized corps.

Also, some of the countries on Earth with the biggest quality of life happen to be some of the most democratically run as well - Switzerland perhaps being the most striking example.

The sheer amount of effort put by those in power in making sure those below them don't get any ounce of power also shows that they see the potential risk to their status if some of these things happen - thinking here specifically of the huge union busting industry, and of efforts to discredit any leftist candidate that makes it onto the world stage (like the disgusting accusations of anti-Semitism against Jeremy Corbyn, or the insinuations of being anti-black against Bernie Sanders).