My first entry level job required C# knowledge. So I went to the nearest Barnes and Nobles and read the Microsoft guide cover to cover. I was not a C# major in uni but being able to study, abstract, and internalize concepts was something I did learn.
The usual retort is why not bring someone in as a junior, train them, and give them a raise to market rates? But then you’ve invested x amount of dollars on someone and y amount of time to bring them up to speed when you can find someone who already has the skill you need and they can hit the ground running.
Even worse, some junior developers do “negative work”. Work that is so bad, you have to take more time to undo the damage than just doing it yourself.
Whether it’s right or not, the only way for a potential employee to break that cycle is via side projects that they can show as experience.