Not that I'm entirely onboard with it, but often you don't have a channel to communicate with "the people who can change the machine", only the cogs in the machine.

When you hate the machine as a whole, the cogs are also in scope.

It increases costs for the machine, and eventually it realizes that cogs are cheaper when they're not getting yelled at all day.

It gives you satisfaction. That's the whole value and it can be worth a lot to not hold bitterness long after the problem has passed. I agree with your parent. The cogs are part of the machine, they don't deserve any sympathy just because they chose to do bad things for money any more than a robber deserves sympathy because he's poor.

Depends on your goal. If you want a better machine maybe hating the cogs doesn't help.

If you goal is to not have a machine at all for some particular thing, then potentially no one wanting to work a job that does that thing might be an effective way of abating the machine from doing that.

Although inconveniencing bureaucrats handling disability benefits is probably a poor starting point no matter what your opinion is.