Is there ever a point where a single person has "built most of the product"? At that stage, the product has so much evolution left, that early employees are goi

Is there ever a point where a single person has "built most of the product"? At that stage, the product has so much evolution left, that early employees are going to be critical to shaping and developing it. It's almost certainly a matter of viewpoint and attitude of both the founder(s) and early employees though, so discretion is required.