What your evidence then ?
An example.
Go to any page on Facebook to do with any kind of news whether it's a major news site or anything else, any kind of political thing, any kind of....actually anything. Same with Twitter.
Have a look through the comment sections of both.
Analyse their comment styles, their phraseology, etc.
Then look at how their profiles are laid out (do they have profile pictures, do they have matching cover photos, do they have any detail whatsoever made public (whilst not a 100% foolproof way of checking, the vast majority of actual people have far too much personal information available to anyone so it's a good indicator) and then look at how they post, how many times, when they post, etc.
Twitter has a very easy indicator by the fact that nigh on every Russian fake profile has a long 8 digit number following a randomly selected name that's been cut off due to handle character limits (for example, a 'David Smith' would have a handle like 'DavidSmi82039400').
There are plenty of twitter profiles for instance dedicated to outing troll farms and 'bots' (they should be called something else because they're real people peddling fake profiles) by analysing the time of day they post, how frequently they post, what they post about and so on and it's enlightening to watch that directed hive mind spread.
How many of those comments are actually coming from real people who are who they say they are on their profile and how many are coming from dedicated troll farms (that we know exist) that comment and tweet from 8am to 8am Moscow time, every day for years on end? We know full well they exist and we know exactly what they do.
Now imagine how often those comments show up whilst people are idly browsing. You take them in subconsciously and then eventually they cement in your head.
Add in the echo chamber that everybody surrounds themselves in, only sharing and liking stuff that they know they'll get positive reinforcement from. We don't like thinking for ourselves too deeply but we'll take in just enough so that it feels solid in our heads and so we can converse about it because we sure as hell don't like being on our own with anything that we might consider our own thoughts.
Add in real people (friends, family, coworkers, acquaintances) actively sharing content (memes, links, videos, etc) that has been curated to garner a reaction and be shared repeatedly, ad nauseum and the propaganda spreads and spreads.
Those messages being seen over and over again, comments being liked and made so that you fit in like a true sheep, then discussed outside of the internet with people close to you to further reaffirm the echo chamber and then suddenly you've got a political agenda that you never thought about. You've been swept up in the hysteria when previously you had no idea whatsoever and no feeling one way or another about it.
Think about all the young people who were never previously interested in politics and how many of them did their research or just agreed with their mates and voted a certain way, how many listened to their parents and voted the same way. How many old people who have lived their lives in an echo chamber and have no hope of changing the way they see the world have had their minds warped and directed to think certain things automatically over years and years?
You might never have given a toss about immigrants for example, might never have met one so you've got no feelings one way or another, you might not work in a job (and there are actually very few) where you're at risk of being undercut by immigrant workers so that aspect of the hatred towards them has no effect on you at all. A personal example is my dad who has probably never met a Muslim in his life save from going on holiday to Abu Dhabi and Dubai once with my mum but he despises Muslims and he's convinced they're taking over Britain despite no factual basis. I've asked him why and he can't tell me. He said today when I remarked about the picture of all the G7 politicians surrounding Trump that Trump was a genius and Merkel is a Nazi. He's got nothing to back it up with but I know full well he's been fed these beliefs on a steady diet for decades. It just happens to people without them ever being aware of it.
Suddenly you're bombarded with messages from online, messages from TV, messages from radio, messages from people around you, messages from everywhere and so you vote Brexit despite having done no research into our sovereign rights whilst in the EU, who decides our immigration policies, where the immigrants generally settle, what jobs they get, what benefits they get and how that might all be changed (or not) due to Brexit and how that in turn affects you and your life and your ambitions and what you're entitled to.
We're very easily manipulated and it happens on all sides. It just so happens that Russia's side won in 2016 because everything since has played perfectly into their hands and their plans. None of this is innocent, it's all a game and we're pawns because we've got no real power. Our only power is voting and that gets hijacked by people with much more to gain or lose doing everything they can to direct our minds to do what they want.
The idea behind it all is why propaganda works and it's exactly the same as advertising. You analyse what people want to see and think they want and appeal to it, even if they have no actual quite what they want to see and what they want, which most people don't.
Brexit was a great example because neither side had a clue what Brexit would look like because it had never happened so they sold it on buzzwords and phrases to appeal to you and get masses of people whipped up in one way or another.
/tinfoiltruth