Think about it this way. Nobody starts off knowing or having mastery of a task. Military aviation works on this principle. That a person should get an MOS out of boot, go to school to learn some basic background about the job (ideally), or to a training command to learn the hands on about the job and then school later. Taking an 18 year old who's never turned a wrench in their life and turning them into something of a subject matter expert in approximately 4 years.

But that's still 4 years to train that person with no prior experience. And experience is what keeps things running. The aviation industry as a whole is just hemorrhaging people. Experienced people are retiring every day and there's not enough new people coming in.

Back in the day my father used to do piece work machining for Eton and McDonnell Douglas. He's in 74 now. The median age of most of the guys I work with? 55. I'm on the maintainer side of things so I don't know about the manufacturing side. But what I do know is that even having an engineer on site doesn't always trump having experienced people to teach the job, supervise it, and fill in the disconnect between engineers and maintenance or builders.

So while I wholeheartedly agree that it is possibly and even expected that instructions should be made so that a novice can follow them, that's not the whole picture.

And there is a disconnect. Working from engineering drawings can be a nightmare. Some engineers have never walked the space they are making the drawings for. They don't know the problems that can crop up when they want someone to install wiring through a solid bulkhead or a wet sealed area like a lavatory. They ignore the fact that this wiring can't interfere with the hydraulic lines running from this bulkhead to this frame. These are problems I've run into and only experience has told me that hey, this isn't right, we shouldn't do that.