I do agree that a product that functions on bad code is better than no product at all. If there where very terrible design decisions made in the beginning. This could have a very negative impact as the business starts to add customers.

A terrible codebase will _eventually_ fail to serve customers for a few different reasons. Scalability is huge and may be very difficult to find performance problems and fix. maintenance time, and time to add new features are places where a terrible codebase will eventually impact a customer.