To be fair propagandists generally don't have to aim high. They only have to shift the undecided and uninformed opinions a little bit.
You want to see some of the crap the agencies were pushing out pre-Brexit and it worked, so I wouldn't classify the average UK citizen as much to be contended with (I am UK as well for ref).
The only good thing to come from Brexit is that for some people they woke up and smelt the more expensive coffee than it used to be and had some self reflection. I have spoke with a good few people now that were like ‘I was lied to’… well duh.
Same playbook as scammers, you want to focus your efforts where they are most likely to have the desired effect, and those who fall for the obvious lies will always be more easily manipulated than those who require a more subtle approach.