The internet went from subculture to being the mainstream culture, especially for politics. Roughly the point at which everyone started participating in sharing memes on Facebook as the successor to email forwards.
This made it valuable enough to be worth destroying.
So all kinds of bad actors started creating appealing, emotional, and false or misleading content aimed at this kind of sharing.
Polarisation is deliberate. Some of it from the media, some of it from parties, some of it from random bored channers, some of it from the unemployed and upset, and some from intelligence agencies and their contractors.
(This has had even worse effects in countries where democracy and media are young and fragile.)
This made it valuable enough to be worth destroying.
So all kinds of bad actors started creating appealing, emotional, and false or misleading content aimed at this kind of sharing.
Polarisation is deliberate. Some of it from the media, some of it from parties, some of it from random bored channers, some of it from the unemployed and upset, and some from intelligence agencies and their contractors.
(This has had even worse effects in countries where democracy and media are young and fragile.)