Like one month almost all their posts are about COVID and the next month almost all their posts are about BLM.
But the "current thing" often isn't a new thing, and instead touches on some core value. For example, people who have never been to Ukraine or know anything about it still care about Ukraine because the situation speaks to issues of violence, freedom, honesty, safety, etc. And people who have never watched a college swim meet care about the trans swimmer because it speaks to issues of fairness, inclusion, gender, etc.
I think there's some validity to pointing out that we don't all have to weigh in on national conversations or lose sight of the bigger picture. But I think it's also a way to try to shut down conversations using a blanket criteria: new, popular conversation == bad conversation. That philosophy can't reasonably be applied to all new conversations without doing more harm than good. In my experience the "current thing" critique is very selectively applied to discussions the commenter is opposed to or bored with, which is subjective and very personal.
This has nothing at all to do with the correctness of any of the positions, just their pervasiveness.
So do you. So do I.
It's not a coincidence, and it's not the implied other explanation.
It's because the structure of vote-sorted top-N list sites like HN, Reddit, and so on, focuses most people on the same short list of topics.
We will all bump into each other again, whether or not we have any intention of doing so.
We're all chatting on the first two pages of stories. We will all collide frequently with people holding similar hours.
I'll give less benefit of the doubt with the next troll.