Sorry to disappoint you, but they were always racist.
They were the racist pricks at school who picked on the quiet kid, they glowered at the assertive one, they didn't invite them to birthday parties and they called the non racist kids variations on a theme of -lover. They were the ones who behaved worst of all for teachers of ethnic minorities, would complain they couldn't understand what they said, had their Mums calling in about detentions saying 'She's just got it in for my son'.
They were arseholes to shopkeepers, takeaway staff, bus drivers, members of the public, shoving kids who didn't know them out of their way.
They got jobs where sharing racist jokes was acceptable and went out at the weekend and would have a go at anybody who wasn't like them on the basis of their ethnicity. If they were out of work, they'd complain about the woman at the Job Centre, the doctor who wouldn't sign them off sick, the bloke who wouldn't give them beer and fags on tick, that they can't get a job because of <insert ethnicity/Nationality/rough continent here> taking the jobs. They'd complain about housing, neighbours, everything.
When they had kids, they'd repeat it all over again, teaching their kids the same racism, claiming that <insert ethnicity/Nationality/rough continent here> was the reason why they didn't have a bigger house, a council house instead of a council flat, more money, a big car, a better dog, more trainers, better holidays, any failure in their lives wasn't their own personal failing but the fault of others deliberately targeting them, never because those others were smarter/hardworking/talented/nicer/just plain lucky - success of others was a direct attack upon them.
What's different is that, thanks to the internet and social media, it's easier for them to find more like them, to whip them up into a frenzy, to promise them the protection of numbers, that the police can't possibly catch them all like they were a batch of defective Pokemon. Used to be that they had to find one another from sport, go to the pub, follow the NF graffiti to meetings or just know one another from school/work. It doesn't have to be filtered and disseminated down from an opportunist leader, through the ranks and out to the scavengers - one tweet of lies will reach the bottom feeders and they'll jump to it.