I think we surpassed the “finding community” part long ago.
These days white extremists are manufactured by other white extremists on social media – the closest thing we’ve ever built to mind control.
The underlying grooming strategies aren’t much different to the ones Islamic extremists have been using on budding young suicide bombers for decades, they just throw in a few more memes.
Oh and most importantly, profits. There’s a lot of ad impressions and user engagement on the path from human being to far-right terrorist, eventually culminating in gun-based mass murder that is like Christmas for the gun lobby and for-profit media.