I think, part of the issue is that, as a mass of humans, we tend to be rather dumb. And they certainly don't decide on merits, in aggregate. It is somewhat questionable if they decide on merits even as individuals ( unless we expand the definition somewhat ). But it is possible I got too cynical.
It's a paradox: on the one hand, if we were dumb en masse, it's hard to see how we could have developed so far technologically and cultivated such complex societies.
On the other: I have to agree with you, there is too much of a pattern of bewildering behaviour not to.
I think what irks me is this idea that deceiving people to push them towards a specific outcome is a reliable and sound strategy, when we've seen many instances of it having the opposite effect.
Why is it not possible to lay out your arguments honestly and let people decide on the merits?