RiverRat:Well I've only been diving for 4 years but I'll give it a shot from my perspective as a land locked DM that "works" in the industry as a hobby, ........Bottom line is that if you rush people through without A: real world diving experience in varied environments and B: No real MENTORING as I see it, you'll pump out crappy Instructors with no real value to offer their students.
Interesting juxtaposition.... I think you intend the hobbyist and the rush through training to be contrasted with each other, but my experience is that they co-exist.
I 110% agree with you that proto-professional-divers should go for as much "real world" diving experience as they can, and mentoring is a well proven methodology for developing personal strengths and capabilities.
However I 'work' for a shop that is hobbyist. i.e. there is an expenses system but what it pays out does not cover the cost of petrol to the dive site, let alone over-nights and hours of work.
The shop also pushes forward training like crazy. Become a DM! Become an instructor! Become a staff instructor!
You could argue it is all money through the till (it is) but it works at a different level as well. More dive master trainees makes for free rescue divers during courses. More newbie instructors makes for more 'teaching-for-certs' which does not qualify for expenses. More staff instructors means more low cost ways of making more divemaster trainees.... and around it goes...
And unfortunately because the training sites are two quarries, it is possible to get all the way up there with little 'real world' (sea?) experience even in a hobbyist environment!