I've been lurking on and off here since 2014 and I officially joined in 2017, right after the site came back up after seemingly been taken down forever for like a month. There has been a distinct shift in the culture over the years
I'd say part of it has to do with Null's brief love affair with the far right during the peak IBS years and then the fact that everything just became more politically charged in general since 2016. Before 2019, the right-wing spergs were largely confined to A&H and to a lesser extent, Deep Thoughts as well as a few specific threads in Community Watch or for specific political lolcows like ADF and Brianna Wu.
Then the Christchurch tragedy changed a lot of it, part of it would be due to 8chan's demise having opened the floodgates.