In what way is making a counter point disingenuous?

It reveals that your intent is not to comprehend another perspective, but to insist upon your own.

Why do I need to just blindly accept what someone says without any pushback?

The thing that you’re being asked to accept is that this someone believes what they say they believe.

Nobody’s asking you to blindly assume that this someone is being honest, but making a counterpoint is not the same thing as asking clarifying questions to probe their perspective for the inconsistencies that would indicate deception.