It's all a fancy optimization problem. Each project can be broken into tasks that take X amount of skill/experience and you have workers with varying skill. If you only have high-value workers, you'll be wasting a lot of skill/experience on the menial tasks. If you only have low-value workers then some projects will fail because none of them meet the skill thresholds.
As a company you want a diversity of workers to allow you to better optimize.
There is some merit to that but what I see over and over is companies try to use too much.
Most menial tasks senior guys have figured out how to automate. We hate menial repetitive tasks and find ways to eliminate them so the ROI of having a senior guy is yes payroll is higher but you have less headcount.
There really isnt anything new being done. Containers have been around for ages ( Solaris doms / freebsd jails )
What I see is companies prematurely optimizing by saying they need portability and multi cloud strategies before they have achieved profitability.
Multi cloud is expensive and difficult and if you don't have a successful business you really don't need it to be portable.
Just some observations from someone watching various business models
As a company you want a diversity of workers to allow you to better optimize.