It's certainly true in my experience. The main thing that makes a difference is simply how curious and interested you are.

Plenty of graduates simply got into to it to make money, and have no real deep interest. Some of them love the theory but hate the practice. And some of them are good at both of course.

By contrast, self taught people tend to have personal interest going for them. But I've also worked with self taught people who had no real understanding (despite their interest), and who were satisfied if something just worked. Even if they are motivated to know more, they are often lacking in deeper theoretical computer science (this is a gap I've had to gradually fill in myself).

Anyway, the determining factor is rarely exactly how they acquired their skills, it's the approach they take to the subject and personal motivation and curiosity.