Two reasons,

1. CMU is the top CS school nationally; the basic quality of the education makes up for the lack of previous experience

2. CMU crafted a program specifically for students without previous experience to counter this effect; most schools do not

Perhaps CMU's specializations could be applied to Howard?

I think it's a dangerous myth, and I also have plenty of anecdata that matches yours. I only switched to software engineering partway through college, worked hard, and had a great job 3 years later. And people can always start in a basic position and spend their career improving and moving up.

Ones man's anecdotes are anothers statistics. I haven't seen any data driven evidence for this, but let's use a thought experiment: would you expect it is more likely for professional athletes to come from a background of playing sports and being active from a young age?

I think most people would say yes except to play devil's advocate. Becoming a top caliber athlete requires years of conditioning, experience predicting trajectories of fast moving targets, ability to read your competitors, mental fortitude, flexiblity, and more. Why would we expect a field that prides itself with top caliber professionals in a competitive environment to be any different?

Are teachers, accountants, mathematicians, scientists, doctors, or lawyers known for practicing to get into their respective fields in elementary & middle school? Not so much. Even for the most demanding fields, we expect them to begin to specialize only in their high school years.

To my mind, the fields which are known for requiring training from childhood are sports and the performing arts (music, theatre).

And if I had to guess, I'd speculate this is less because it's intensely difficult to play sports or learn to play music, but because so few people can become professionally successful in these fields (there's only room for so many sports/music/film stars). CS doesn't have this problem (the demand for programmers is skyrocketing), so we shouldn't expect folks who learned to program in childhood to have any more than a mild-to-modest advantage.

Mathematicians, scientists, and doctors absolutely! Catching and dissecting frogs, joining math clubs, debate teams, etc. It's not a requirement but when I think of the best folks in their respective fields they did not start in college. It's not that they've specialized from a young age, but they had long term passions for the tools useful for their field.

What early education provides is a safety net when things become tough. My classmates without this preparation had a much more difficult path and many eventually dropped out. The psychological effect of impostor syndrome is a component to picking field to study in college; those who feel they have a harder time than their peers are less likely to continue in the field long term.

Sure, but I wasn't talking about what it takes to be the best in your field. I was talking about what it takes to even be given a fair shot. (Original comment: "If you didn't spend a lot of time with computers on your own before college, you're not in the running.")