The article 4 times finds the idea that the entry threshold for programmers is very low. Why is? And since it is not so high, why is there still a shortage of personnel?

Employers don’t need people who just crossed the threshold. They need those who know not only how to cross the threshold, but also to enter the room through a closed door, to climb into the chimney, along the way building a staircase of sublime materials, parallel to performing Schubert's valves.