There are several steps missing from:

A startup founder uses AI to create an MVP

to

They secure funding based on the demo

to

They find themselves unable to move beyond that initial prototype

I have trouble believing tech investors throwing money towards a founder that shows a vibe coded product without anything else. The product might be vibe coded, BUT the founder show some traction or discovered a new market or something besides a demo. It does not really matter how a founder did the MVP, they did not create google. They just showed, through the MVP, something to investors. What happens next, after money, i doubt it's vibe coded.