I think people not being able to answer “how does it feel” questions is partly due to the cultural quirk where “what do you think” is replaced with “how do you feel”. Meaning even the asker is in fact posing the question as “what do you think”, rather than inviting actual reflection on one’s emotional state. Think of TV interviews for example.

I also suspect that there’s a subtle desire to make the answer a bit more inarguable. Because it’s socially acceptable to argue about one’s thinking. Less so about feelings. “All feelings are valid” is taken to mean that anything that follows the phrase “I feel…” is automatically true and you’re not allowed to disagree. Which is precisely what the “all feelings are valid” is not about. “All feelings are valid” points to the subjective experience of an emotional state. A war veteran freaking about fireworks is valid. A war veteran saying fireworks mean they are actually getting bombed is not. Rape victim feeling insecure when walking alone is valid. Rape victim saying everyone’s trying to rape them is not. A highly nuanced and volatile issue which people really want to reduce into very simple dogmas.