The main thing which annoys me (and I'm not implying you have this view) is statements to the effect that "nurses claiming there's no benefit to being a doctor, and that doctors are impractical and useless". Both doctors and nurses are necessary; neither is sufficient.
Well I agree with you about doctors and nurses but think the analogy is totally invalid as far as engineering is concerned. Perhaps it was true 30 years ago or is still the case in very large organisations and factories but not in the places I've worked.
In a relatively small organisation, it makes no sense to employ a technician and an engineer. It makes far more sense to find someone who's highly skilled both in theory and practically and can do both.
That presumes a technician is capable of doing an engineer's job, and vice versa. While there can be overlap, in general it isn't true. I, for example, can solder, but not well enough for production quality. OTOH, I can find a way of making an optical receiver with 180bB dynamic range from jellybean low tolerance components, etc etc.
There's not much need for people who can solder to production quality these days and even when there was, it was seldom done by people with any theoretical qualifications but by assemblers who often knew nothing about electronics theory. There were electronic assemblers at the defence contractor I used to work at. They knew the resistor colour code, IC packages and could solder to a very high standard but didn't even know Ohm's law.
It was a too brief and not very well chosen example on my part, and you are reading more into the specifics than they deserve.
Instead of soldering, I could equally well have chosen examples relating to maintaining development environment infrastructure, or IT infrastructure, some test harnesses, or routine elaboration/mutation of designs to meet the next customer's requirements. I have little interest in, and am barely competent to do those vital activities. Cf a nurse in a hospital.
Instead of the optical receiver I could have chosen examples related to architecting high-availability telecom systems and understanding failure modes that can never be avoided (e.g. "split brain syndrome") or the limits on time synchronisation, or selecting which technologies are best suited to nextgen products and which should be avoided, or inventing and patenting novel techniques etc. Cf a doctor in a hospital.
Doctors tend to be incompetent at nurses's tasks. Nurses do not have the training or skills to do the doctors' tasks - but some of them think they do, usually because they never see/understand what a doctor does and how they reach their decisions.
That presumes there isn't enough work for two people.
That presumes people all have the same personalities and skills. They don't. A classic mistake is to try to make a team with everybody having the same team role; see Belbin's work for why that is suboptimum.
So yes, it is always being wary of assuming your experience is generally true. Usually a subset of one person's experience corresponds to a subset of situations.
Yes, in larger organisations there will be more of a tendency for people to specialise: a programmer for the software, an analogue engineer will design the part with filters, op-amps etc. a digital designer for the FPGAs and a technician to get the prototype working. Smaller organisations will tend to employ one or two people and may use contractors and consultants to get extra work done and fill in the gaps in knowledge
Specialisation can occur, but does not have to. But you are missing the concepts I was alluding to.
Very briefly, one cut on Belbin's team roles is to divide them into "chairman", "ideas man", "critic", "worker", "finisher", "contacts man" and a couple of others. Each role has its required strengths and allowable weaknesses. To have a successful team, you need different people to fill a cross section of those roles.
A team made up of "ideas men" will be very inventive, impractical and nothing will be shipped. A team made up of "critics" will be boring, practical, and nothing will be shipped. A team made up of "contacts men" will have lots of customers, but nothing will be shipped. A team made up of "workers" and "finishers" will ship the same as everybody else.
But a team where a "critic" selects the sound ideas emitted by an "ideas man", gets them made by a "worker" and polished by a "finisher" will be able to ship things to clients discovered by the "contacts man". And the "chairman" will get them all working together.
"Engineers" are usually primarily "ideas men" or "critics", with a secondary "worker" role. "Technicians" are usually primarily "workers" or "finishers", with a secondary "critic" role. Vive la difference.