I agree to a certain extent. Social media creates an echo chamber when you have established views. However, when you don't have an established view, whoever has paid the most money to facebook, google, twitter etc, gets to try and sell products or ideologies to you.
Everyone has topics/subjects/ideologies that they don't have a strong view point on (in many cases, no viewpoint at all).
I know very little about cars, even though I've spent thousands on them over he years. I've little interest in them. I've owned and purchased cars for years, but never watch motor racing, go on any car related websites etc, therefore it's probable that I could be more easily swayed into buying a particular car than a car enthusiast, cos I know sweet FA about them. I'm also much less likely to be loyal to one brand of car. I'm a dream customer for a car manufacturer's marketing department, it wouldn't take much to persuade me that one type of car is better than another, because of my lack of knowledge and lack of interest in carrying out any research.
Now if BMW paid an analytic company millions of £s to use algorithms based on personal search history to pinpoint me, and I received ads, saw other people posts, was recommend films, books, blogs, articles showcasing how brilliant BMW's are, and other's how crap Audi's are, I'd probably be more inclined to buy a BMW, even though its a bit unfair on Audi. Tough shit, Audi should have spent more money on advertising.
Cambridge Analytica did the same thing with politics, in multiple elections over the world, the only thing is, they used (by paying facebook millions of $) the results of personality test quiz that hundreds of thousands of facebook users took part in (thinking it was going to tell them what sort of personality they had). The data from the quiz gave CA an inclination into personality traits, and access to their previous interactions, likes, clicks etc, which enabled them to create profiles that suggested how likley they were to be influenced politically. It also gave them the same access to every friend linked to the quiz takers, some reckon over 80 million profiles in total.
Whatever anyone thinks about this being a conspiracy theory, Facebook and CA were caught doing this in the US and UK. Facebook were fined $5 billion dollars in July this year, £500k (the maximum penalty in UK) in 2018. CA closed down because of it.
I've no idea how much impact it had, and as many have pointed out, it's history now, but it really happened, and I'm sure it will happen again.
PS I've got a KIA, like half of Bolton.