I think that's not quite the way consulting should, and to some extent does, work.
The ideal goal of consultancies like Deloitte's is that they hire a small number of people with experience and combine them with a larger number of young bright people and have them come in to review and advise organizations. The people with experience (so who have worked in that field before) direct the engagement and the leg work is done by the juniors, producing a report for the customer.
As to why companies would choose to use consultancies, there's a variety of reasons, some good, some less than good.
- Outside perspective & experience. The consultancy has done engagements with other companies in your field and can provide that experience.
- Neutral point of view. The consultancy should be neutral to any internal politics within the organization.
- Appeal to authority. Many times organizations use consultancies to provide evidence to external stakeholders that the thing they want to do is the right thing.
Now that's not to say that it always (or even often) works out that way, but in theory at least, there are some not terrible reasons.
Ah, OK, so there are actually people with real industry experience there? What happens with the young bright people when they are not young any more though? Are they expected to leave the company to gather real world experience or are they just promoted to "experts" without seeing anything outside their consultancy?
The trick is they pay the young bright people peanuts relative to what they bill them out for, so then market forces rotate the majority of them out of the consulting org automatically, often into positions at the companies they consulted for or into their own businesses.
So why do the young bright people do it to begin with? They get to work with experienced people, broad learning experiences in diverse industries, networking (= future job prospects), etc.
Well they get some experience doing the consultancy work of course, and yep lots go off to industry after 2-3 years.
IME (Worked for E&Y some years back) about 80% of people who started as juniors would have left after 3-4 years with the other 20% staying to try and make partner.
I have a few acquaintances who grew in consulting to become partners who have never, ever, ever worked in the field they consult for. They've only done consulting, only looked through the lenses they were required to for the job they were asked to do with no real experience in the industry.
The only person I know who ended up at a high-ish position at McKinsey with proper industry experience had as their only job being the founder of a company they worked quite hard for 15 years to build, and sold it. Still, it's someone who only had a narrow experience in their industry which is now advising companies in very unrelated fields.
The ideal goal of consultancies like Deloitte's is that they hire a small number of people with experience and combine them with a larger number of young bright people and have them come in to review and advise organizations. The people with experience (so who have worked in that field before) direct the engagement and the leg work is done by the juniors, producing a report for the customer.
As to why companies would choose to use consultancies, there's a variety of reasons, some good, some less than good.
- Outside perspective & experience. The consultancy has done engagements with other companies in your field and can provide that experience.
- Neutral point of view. The consultancy should be neutral to any internal politics within the organization.
- Appeal to authority. Many times organizations use consultancies to provide evidence to external stakeholders that the thing they want to do is the right thing.
Now that's not to say that it always (or even often) works out that way, but in theory at least, there are some not terrible reasons.