My father told me this after getting his Engineering Degree and ended up being appointed to a position where he was eventually hiring engineers for the department.
Getting a degree is like getting an education on how a ship is built, why it was built that way, what to use to build a ship and how everything works together. However, the knowledge does not equate to skill in sailing the ship, even though the degree'd person has all the requisite knowledge.
The trademan who goes into the profession from school (or earlier) and likely follow in some kind of mentorship (father, uncle, brother etc). This person will be highly skilled in running the ship and have certain intuitive understandings about running the ship that an engineer will not have.
Pound for pound, a newbie artisan who has worked for the numbers of years the engineer has studied, is far more value out of the blocks than a university graduate. They have an eagerness to learn, a humility that comes with being a student all the time and often come up with solutions that work that don't fit within the framework of education.
That's not to say a degree is not valuable, because after a certain amount of time, a good engineer who unlearns certain aspects of education, removes the "ego" of having a degree, will eventually become the master of the tradesman because of the superior background of knowledge.
However, a Tradesman given the drive of continuous learning can equal a qualified engineer of equal years in most cases.
A good quote from "The Resident" - "Doctor schools are great at teaching you many ways how to save a patient, what they don't teach you is how many ways there are to harm one"
I find this to be true of most education.
It is good that what works for your company, works. Doesn't mean it's a monosolution that will work always.
I have heard this nonsense throughout my career. There is simply no way that you can learn in depth theoretical knowledge of structures and nuclear science (which is my field) on the job.
Have a job skill is good, but very often your intuition is wrong. This is why we have graduate that go through years of rigorous training.
I have heard this excuse a lot from people who are constantly making excuses for not wanting to studying anything and therefore feels undermined themselves.
There are very few people you can build up a solid theoretical baisis on the job and in certain fields it is simply impossible.