I first thought this "only abnormal people left to communicate" comment referred to online communities. But it could also refer to people who ignore the shut-downs and hang out in smaller groups regardless limits on gathering etc.

In my country there is no clear distinction of what type of people make up the crowd which is "still" socializing. While you get some pockets of conspiracy theorists, covid-deniers, mixed with conservative or right-wing elements, the left, or even politically abstinent are also there. It doesn't make them all abnormal people. There are some who I have perfectly communicated before the pandemic. But the pandemic has made many people mentally struggle (without a need to lump them all together into "abnormal").

My guess is those who have already been (mentally) vulnerable are now even more so because the world around them is becoming even more depressive/depressed. It's not that there are only abnormal people left who to socialize with. It's because many just die because they were anyway hanging on to a bare minimum before. It doesn't require the presence of "abnormal" people to kill them. It's enough when a support structure that they previously had (a friend, a source of fund/support, etc) simply breaks away. it's not an addition that hurts them but something that is taken away. (so it's actually less complicated/complex/conspirational and more ugly/sad as to why this happens)