Not OP, but in my experience it's the customer.
Some contracts (mostly government) have a strict definition of what an FTE is/can be. Because it's the government, instead of having a nuanced understanding of the field, they treat everything as a series of buckets - "you have a college degree? You're Engineer II. No degree? Clearly Engineer I." There's some wiggle room with technical experience and whatnot, but it's tricky to do.
So, when the government customer puts out a request for bids, they'll say something like "we want a system that does X, Y, Z, and we expect this to require 3 FTE 2s and a part time PM for 6 months" - generally establishing the upper limit of what they'll pay/how many hours should be billed to the project. (This gets interesting when you realize that the customer doesn't really know how the sausage is made, so they talk informally with contractors to get a feel for what's possible/go to a team they've worked with before, get a feeler for what the requirements should be for a project/what to expect cost wise, and only then put out the formal request. 9/10 this means that the government PM has a team they want in mind, and basically has the team write their own requirements sheet).
Any way, long story short the credentialed designers look good on a contract, and produce valuable designs that can get approved/validated by the Powers That Be, while the mechanics who implement things come up with the product. Both are providing value, just in different ways.
Also, sometimes you need to start with a lovely design, even if you know it will never survive production.