I was a IC consultant for a big 4 group at one point.
Very successful in my domain on a very successful project.
I wrote an insane amount of code but more importantly I wrote libraries across multiple languages that prevented an insane amount of code from being written.
We would have literally 1k people during quarterly planning and did distributed agile and all this org stuff
(It was interesting anthropologically to me because I operated outside the game, I was just waiting for a ~non-compete I had signed for a profitable technical co-founder exit to end to jump back into starting a new company in the same space.)
And the whole thing worked, and I was very high profile on the project as probably the highest paid IC and the company hired me away from the agency and I worked their until starting my company.
There are 3 layers, the deal makers, the coordinators and the implementers.
You cannot easily automate out the deal makers because they are trust, legal/contracting and power (they use the resources of the firm to allocate: people, resources, etc.) loci. Someone has to hang if stuff goes wrong and someone has to deal with executive petulance and fragile egos.
Now lets look at the middle layer and implementers.
Let's assume for a minute we are looking at a big project where the existing company has hamstrung itself with silos and infighting and low productivity teams, this is just framing to understand the next part, it can cut either way.
The middle layer in consulting is big because other companies have big middle layers as well, and basically what is happening is tribal warfare, you need bodies and voices and change management teams to propagate what is happening otherwise the existing group will slow play the leadership and the project never gets done. If the middle layer is 1 to 1 every native sees they can be replaced. Many big 4 allow poaching for this very reason. The threat of non compliance and then also giving an easy congenial out for people who are ready to exit the consultant lifestyle.
The implementation layer is then able to be done, and it's done by juniors mostly because juniors don't have to be politically savvy, they can work to task.
Just a small slice or things I realized while consulting.