I've worked in the plastics industry. A lot depends on the kind of mold of course. A mold can be somewhat complex when all is said and done, and made from a com

I've worked in the plastics industry. A lot depends on the kind of mold of course. A mold can be somewhat complex when all is said and done, and made from a combination of parts that have to be ordered, or materials that are difficult to work such as hardened steel. Producing multiple pieces that fit together correctly and aesthetically can be an art. Whether the mold actually works in your machine without problems depends on the quality of the mold maker. And it could boil down to the fact that mold making is a mature industry with a lot of established supply chain and lead time expectations, and nobody is trying to rock that boat. Of course you don't want to spend all of that time to get a mold that you can't use because you screwed up on your end and forgot to add a needed feature. The world has not moved away from the benefit of a physical object that you can hold in your hand and see that it's actually right. And the 3d printed prototype can also let you check other things while the mold is being made, such as the fit of things like circuit boards, buttons, and connectors.