Most managers love to repeat "saying it's not my job is terrible attitude" while assigning unreasonable targets and stuffing items in the Sprint to the extent that even sneezing hard will make you overrun your deadline. So I am expected to deal with non prioritized work with a smile so that I have to steal from time set aside for my family in order to make the sprint target? How is that not bad mentality?

Yes, you are expected to deliver the message to García without question or complaint. Managers love initiative and self-reliance, but only in service to faithfully obeying their commands.

It depends on why it isn't my job. If I have the ability and the capability and the time to do it and probably a few other things, then it's bad. But framed as a specialization inside a giant company, where it's not my job so if I do it, I'll do a bad job and make mistakes and cause more work for you and me, and end up being a -10x engineer, please tell me it's not your job.

There's a limited number of people I can get to know within a unit of time. This means there's a limited number of people I can care about. If there's my coworker Dave who has three children, two dogs, depression, and talks to me on lunch break about all of these, and asks me to take over his task, I can do that. If a random guy I've never seen before comes to me and wants something, I'll naturally look for a way to get him to fuck off

I mean this in the broad sense: like asking somebody in the sales department to lead a mission-critical database migration. That is in no way their job.