Surely the ad you are referring to is only asking for some capability or knowledge in the other skills, rather than being an expert. I would expect the average IDer to be able to do some basic graphic or mechanical design, even if only to explore ideas, but certainly not to the same standard as a graphic designer of engineer.
The alternative is the classic ‘student job’ ad, where they just ask for literally everything.
“Seeking junior student for part-time job in retail environment, must have 10 years experience in all things retail related. Those without experience do not apply”.