The decision to run ads for money is itself highly political: it completely undermines the idea of free competition of ideas solely on their merits by heavily advantaging those ideas backed by money.
And if a lie can win out over the truth, this would be the mechanism that does it. It is certainly not coherent to complain about a "mob" "shouting" down an idea while trying to out shout them through money.
The points on monopoly are valid and serious. But the focus on a single de-facto monopoly, Facebook, undermines and muddles the point.
There are other de-facto and even real monopolies in broadcast media that are more influential and far more restrictive in content, Sinclair for one. I can not see how one could coherently oppose Facebook's de-facto monopoly while ignoring others that are actual monopolies, unless we make some arbitrary distinction on the technology used: radio and TV can monopolize but not web based technologies.
And lest one think that there are orders of magnitude difference between the TV/radio monopolies and Facebook, I will point out that:
1 We (the users of this site) are self selecting technologists and are much more focused on web issues while being far less dependent on non-web based media than the vast bulk of the population.
2 The intentional effects of broadcast monopolies on voting patterns are so large as to be easily measurable. Facebook's intentional influence, if it even exists, is certainly not obvious.
3 Twitter is in fact only read by a tiny segment of the population: The number of US man-hours spent listening to talk radio on monopoly owned stations vastly exceeds the number spent on Twitter where at least there is some possibility of accidentally seeing a contrary opinion.
So yes monopolizing is a serious problem and desperately needs fixing and it is vastly wider than web.