Why is the recruitment of single-chip microcomputer limited to under 28 years old?

If you have work experience, I have never heard of it. If you are a novice, it is estimated that your learning ability over the age of 28 is not as good as when you were young. Starting new skills is slow, and the physical strength is not as good as that of young people who just graduated. Unable to add classes, the project progress is slow, which will naturally cause certain losses to the enterprise. You know, the single-chip microcomputer looks like hardware, but it is actually similar to a programmer and needs a lot of physical strength.