I was perhaps, as usual(?), overemphasising my point. In different industries, and in different roles within a given industry, either might be a better solution.
My personal career has been something like 90% intensely technical and analytical. My second manager out of uni was a great guy, and also experienced in the field in which we worked (automotive NVH). Within two years I was far beyond his help in technical stuff, and have never looked back. One reason I learned so quickly was that he was interested in what I was finding out, so we picked a lot of things up together.
Since then I have had 'technical' managers and 'political' managers, and frankly, the efficiency gains from having someone who knows how to make the company system work and trusts my result without necessarily understanding the underlying details greatly outweigh the additional robustness in the process from having someone second-guess me technically. Oh, I'll make one exception. My first supervisor during, and after, uni was a very very very talented analyst, working for him was like one long tutorial, and we worked on some fantastic projects.
So, I think in the particular case of analytical automotive engineering it is very useful to have technically gifted engineering supervisors and managers to set the young engineer on the right path, but after the first few years the manager will get a better result by letting the engineer make his own mistakes.
Just thinking about that para, in theory of course the inexperienced engineer could benefit from learning from a technical mentor, rather than his direct supervision, but at least in my case that does not seem to have happened much. I think that is a cultural thing in the UK automotive industry - grunt engineers don't tend to be technical mentors to the kids. If we are working with people on our own percieved level of experience then we learn off each other, but the more 'one way' technical flow in a mentoring role is seen as what? a waste of effort? boring? training up your future competition? I don't know what, to be honest.
This is a shame, I've found that educating/mentoring the right sort of engineering graduate is very enjoyable (at least for me!) but, having a somewhat prickly manner, they have to be the right fit.
Cheers
Greg Locock