MVP implies that you show them the most valuable feature. It can simply be a mockup too! What you need, in my opinion, is basically your core proposition. Like if you build a killer robot, showing that it can hit any target you click on, is nice.. even though it might not be able to move. If its a webapp, don't focus on solved problems, like Logins or SSO but rather show me what your "x for y" can do. After all the p…
People want a product that works for MVP in most cases. If you are a brand new tech that no one has ever done, okay. But if there is even 1 competitor that kinda works, a mock-up is worth 0. So I think depends on the market for the product.
Like under this advisement apple never would have gone into phones. There was literally a phase were we were joking that somebody is building the "uber for X" or the "tinder for y" and im pretty sure a lot of those did get funding without having a single line of code in their names.