I think that associating with any ingroup is broadly dangerous, of course this isn't without warrant and the fact is that in the current climate (politically, socially) there exists a strong ingroup bias. But not only this, the actions that other members of a group that you identify with are readily associated with you. This leads to the social atomisation that we are seeing, especially in young men and boys, and also formation of new groups (see: Jordan Peterson fanboys).
To explain this claim, to associate with a bad egg can cause you to be completely and fully excluded from social communication with some people. We can also see this institutionalised as the government making lists of people who associate with other people. Now, I think this is a generally obvious observation to make, but the power of the internet has allowed for free association like we haven't seen before and the power of filter bubbles to be created dynamically exacerbates to this problem.
Why then, has this seemed to become a larger, more visible force since around 2014? I think this is a harder question to answer, but it boils down to the big mess that is Gamergate. For the first time on the internet a controversy that spanned multiple sites and poured into real life had happened with real consequences. I remember at the time being an administrator on a moderately sized Minecraft server and tensions being constantly high about arguments relating to this.
In essence, I believe that Gamegate was a transformative moment for the internet in many ways, a lot of what was seen as inter-forum bickering essentially (4chan, Somethingawful etc.) became very real. I think also it was the point that many trolls realised that a small number of coordinated users could have real world power. In 2015 the first notable modern SWATing (calling in false armed response units to a victim's house) were observed, people had realised the potential impact that they had on people.
I think that a lot of people think that Gamegate directly lead to the situation in the 2016 elections, that of the absolutely insane feats that 4chan users seemed to manage to pull off consistently (and that they try to replicate to this day). A microcosm of this is that of the Shia Lebeouf art project 'He Will Not Divide Us' (post-election). Originally a camera installed on a wall outside the Museum of the Moving Image in NYC, it quickly became a flashpoint for the alt-right & /pol/. They quickly moved to New Mexico which they then moved again from (this time not because of any particular group of people). The climax comes when they gave up the live stream camera for the public and point it at a flag in an unknown location emblazoned with 'HE WILL NOT DIVIDE US' and within 38 hours... 4chan had located the flag using various navigational techniques, within two days it had been replaced with a 'MAKE AMERICA GREAT AGAIN' flag and a pepe the frog T-shirt. After this further, less noteworthy attacks were made against the project and more moves took place.
Whilst I think this has largely fallen out of the public's mind I think it's a perfect show of the power realised by the internet. Very quickly a pivot from some American high-school to college aged kids messing around to a real and powerful tool had occurred. This feeds directly into the problem of association, when you're in a geographical, somewhat contained, social bubble you tend to be able to filter largely un-hurtfully and even subconciously. You just end up not being where the people you don't wish to associate with are. Meanwhile on the internet you could be following someone's account on twitter and there's no indication whether you support their ideas, you hate their guts, or just think the cats that they post are cute.
Couple this with the increasing trend in shielded, that is 'private', communication (e.g. Discord, Facebook Messenger Groups) you have a perfect soup for backstabbing, spying, speculation etc.
To come to a final conclusion, associating with anyone or and ideal seems to be more and more dangerous for anyone which is perhaps why we are seeing a large scale social atomisation. Further to this anyone with ideals outside of the perceived norm feel like they are liable to be attacked for having those ideas, especially when a few people on the internet can make themselves seem like hundreds.
How can we fix this problem without removing the things that make the internet so good to use, we don't want to give up pseudoanonymity but this also makes us forget the person behind the screen. A large cultural shift in our attitudes towards what exact function the internet serves in our social lives. I think that a lot of problems relating to the way that the internet functions for users is that we are finding quite how it relates to our lives.