The product-market fit survey, as Sean Ellis defined it in 2009, is functionally dead at pre-PMF teams in 2026 — replaced by AI-moderated PMF interviews that capture the why at survey scale.

The product-market fit survey — specifically Sean Ellis's "How would you feel if you could no longer use this product?" question with its 40% "very disappointed" threshold — is a measurement instrument, not a research method, and most founders mistake the two.