Good founders can accept failing if they were unable to build a product people want/need. That's hammered into you from the moment you join YC (and well before - PG has been writing essays about this since at least 2005).

This essay is not about that. It's about people who attack a product/company/founder for reasons that are not about a product's functionality but are about their own issues.

This can be presumed to be be true of a critic who actively desires to see a founder's company "crash and burn" (leading to financial damage to them and their family if they have one), rather than just thinking it would be better for the founder to change their product or company direction.