That's a different sort of trap, as it ignores the effects of circumstance (even minor things, like whether organ donation is an opt-in or opt-out checkbox can have huge real-world effects).
It also leads to blaming the unfortunate for making poor choices when those choices have been both constrained and biased by circumstance.
I strongly disagree with that and I believe this kind of thinking is not actually as logical or as rational as you were lead to believe, and properly asking the why question and answering it is fairly critical to figuring out what should be done.
> go with the flow
Go with whose flow? You realize that this is just you piggybacking on someone else's answer to the "why" and blindly accepting it without any kind of verification? This should be alarming, not calming.
Really, if someone somewhere was able to answer this question well enough that they could create a "flow" for you to go with, you can do the same.
It sounds like you've simply bought modern "nihilism", i.e., the "everything is meaningless and nothing matters" philosophy that a lot of logical types seem to believe but none actually live (since it's not workable).
Digging down to whys requires actually answering them, not throwing your arms in the air and saying that the question is unanswerable. It's answerable, there's a reason that you do things, otherwise you wouldn't even be able to exist. "I do things because that's what my machinery does" is avoiding the question. Well, duh. That doesn't mean there aren't reasons as to why you do or do not eat that donut.
It's like if someone approached you asking how a given piece of software works, and instead of explaining the structure and the business logic, you say that it's a bunch of machine code. Wrong level of abstraction, you just dodged the question.