Comments 1 and 2 sound like you have only experienced hobbyist-grade printers and not high quality, easy-to-use, professional tools. Engineers can waste time fiddling and there are many things that make sense to outsource during development, but try a Form 2 and see if you still feel this way.

3 is actually an excellent suggestion. It's important to communicate with production suppliers early and often. But outsourcing early stage prototypes to prototype shops usually doesn't help that much (unless your final production volume is low)

4 and 5 are not true for low cost systems if you have even a small amount of printing and value the speed of your development team.

6. Doing as much digitally/on paper as possible is also an excellent suggestion. Too many engineers rush to build stuff Simulation and other tools are constantly improving. But for full functional testing, ergonomics, industrial design, etc, there is still no substitute for physical prototypes.

Full disclosure: I work at Formlabs https://formlabs.com/ and our mission is basically to solve all of these problems.