Is it inevitable? I am not sure either way.

I think that if you look at real-life Friend-to-Friend groups, this is what you find: clusters of people with similar values. So it it makes sense that the same applies to F2F groups over the internet. But most social media is not F2F groups.

Most (advertiser-driven) social media (including this site) is based on the idea of what I call "implicit ranking": The idea that a user can influence what another user sees (through "likes", "votes", "reports", "bumps", etc.) without having an explicit consensual relationship with them (such as a "subscription", "following", or "sharing" or "direct message channel").

This "implicit ranking" model is pretty successful because it is better at finding engaging content is and probably the dominant form of social media. In contrast to F2F, implicit ranking networks tend to promote controversial content from outgroups because angry users are engaged. We all love to flamewar sometimes, I'll admit it.