Ask HN: Why do people keep blaming others?

This is something I keep noticing in people. Even if they seem to have a broad understanding of a topic (say, software engineering), they refuse to understand why people from a related area (say, project management or design) do things in a way that might not fully appeal to them.

Most of these people generally have a high intellect and are fast learners, not just in their profession, yet they don't seem to be able to see why other people might have different believes.

An example can be found in this video:

https://www.youtube.com/watch?v=HURvJDldVGA

In it, the author talks about why a programmer might hate Scrum. Going into it, I thought they might point out things I, or the dev team can improve to make Scrum fun again. Yet, the only people that are blamed are project managers, and never the programmers, which seems to be the profession of the author. While I somewhat agree with their points, I highly doubt that it's never the fault of a programmer, which is implied in this video.

Another example for this is farming and politics. I grew up in a family of farmers. Ranting about how politicians are destroying our industry was 90% we ever talked about. If I talk to some other people, it's the farmers who are destroying our planet.

Do people actively ignore other opinions to leverage a better outcome for themselves, or are our brains just not able to find a common ground?