Personally, I think...

(Well, I suppose that's an odd start, since half the problem with politics is people trusting their personal thoughts overmuch rather than gathering evidence. Then again, those who do gather evidence in politics, the softest science, rarely seem to find any that upsets their preconceived notions. Anyway-)

...that this would happen with or without any overt government interference. I'm sure that the soft pressure described by Mr. Chomsky plays a part, and that most government officials in democracies are happy that it exists.

But just look at smaller scales: say, at the umpteen "camp A vs. camp B" divisions that come up in one capacity or another on this site. JavaScript is a horrible language that's killing the web, or it's a cool language with some flaws. Go is a language firmly stuck in the 1980s with the goal of treating its programmers like disposable pawns[0], or it's a fluid pragmatic language with an emphasis on maintainability. Apple has a track record of producing shiny overpriced crap, or perhaps innovative products that usually beat the competitors'. Google is an advertising company and absolutely everything it does has some direct connection to invading its users' privacy, or it's a geeky paradise, tech culture's truest representative among large corporations. The NSA is a villainous organization through and through that's killing everything important about American freedom (common opinion on this site, not as pervasive elsewhere) or it's just doing its job and has little, if anything, to answer for. Feminism... well, I think that word is enough.

These are just some of the biggest examples; there are countless others, and obviously you can get far more examples by broadening the scope from tech. In each case, people tend to divide themselves based on their opinions into one of (usually) two opposing groups. Each group is self-reinforced by memes spreading through its echo chamber, each is very confident it's right, and importantly, eventually members of the two completely fail to understand each other, speaking with different terminology about different principles and both almost certainly far from objective neutrality. Some of the camps have some potential equivalent to Chomsky's cited explicit manipulation - c.f. the recent Fear of Apple post. Most don't. People self-manipulate, and they're rewarded with positive emotions generated from discussions with other people that share their views.

In politics, the camps form within political parties, geographical areas, and often entire countries. It would be interesting and powerful to think of ways to reduce this; on the other hand, I don't think it's fair to blame Western governments for what's basically human nature. My suspicion is that people look at the distortion of reality in democratic country X's politics, compare it to censored country Y's, find the proportion too large, and blame the government of X... but miss that a large portion of each side's distortion is natural, and if you subtract that from each side, the proportion gets far smaller. YMMV.

[0] opinions on Go aren't usually that strong, I think, but I've heard exactly that claim from one firebrand on Twitter.