It's a complex truth. Irrelevant or not, you know that whatever figure you give is likely to be what they offer. So you'd just answer if it was the figure you want. Refusing to answer signals that you're asking for
more than you used to make. And it's a pretty clear signal. It's not like they'll just go, "Hey, I guess you're right, wonder why I asked in the first place?"
They've already got it in their minds that you're supposed to get the same old salary. It's not so much bullying as just a different perspective on the world. A mindset. You can try to be that guy who finally shows them the light, or you can look at your options in a pragmatic sense. And creating conflict with the guy interviewing you is not super pragmatic.
Edit: One other point. Something is worth what people will pay, by definition. If someone offers you less than you're worth, then by definition you have a better option. So go take the better option. If everyone is offering you the same figure, then by definition that's what you're worth.