The Internet (social media to be more specific) has helped people with fringe ideas to connect with each other on a global basis, regardless of how fringe these ideas might be. Pre social-media these "fringe believers" used to be so fractured and compartmentalized, limiting their influence and general visibility quite much.
Social media has allowed for these fringe believers to find each other, not just allowed, it's pretty much motivated it by personalizing what content and users get surfaced to them. To put it in not so nice terms: Facebook has facilitated a situation where individual town-idiots unite on a global scale, this allows them to shape the public discourse in ways they haven't been able to before.
Case in point: People throwing around the term "cultural Marxism" these days like it's the most normal thing in the world. When "cultural Marxism" is basically just a reframing of the age-old Nazi conspiracy theory about the "International Jews controlling everything".
Not too long ago you could easily disregard people spreading such memes, as they were rare and single individuals. This doesn't work anymore because the idea of "cultural Marxism" being an actual thing has now been legitimized through massive social media echo chambers.
The sad part is that many of these people often don't even know what they are regurgitating because they get all their information just from their social media feeds. A quick google search of "cultural Marxism" should be able to educate anybody in a matter of minutes, but that would involve effort while "+like" and "share" barely requires any effort and is the far more appealing course of action when users see something that reinforces their beliefs.
In application just because a piece of information exists on the internet doesn't mean folks will be exposed to it. Folks values are reflected, but are also molded by the information that is made readily available to them through there internet habits and social network. If entities censor or place greater emphasis on certain streams of information they can attempt to mold the resulting values of users.
Humans online polarize themselves and split into sub groups. (Amazingly the sub groups can end up polarizing themselves.)
Facebook has never dodged the issues forums has faced.
The core issue is human behavior and nature.
I've seen polarization appear where none used to be before.
My view is that the web often results in a worst case scenario.
1) Text like books, are permanent - once written, you can always revisit them and they don't get erased
2) Voice is very good for real time expression of emotions you feel. But its never permanent, or easy to revisit. That momentary flash of emotion was never bottled and dissipated.
The net combines the worst of it.
Have an angry thread? You get triggered and write an angry response - and then go away.
Meanwhile, people keep coming to the thread, and it feels like an ongoing conversation - and now they start getting triggered - over and over again.
Its like having people exposed to an anger stimulus, randomly and at mass scale.
So its not just more apparent: It's not just tribe/group discovery - its straight up tribe/splitting and creation.