The best programmers i've worked with don't have degrees in computer science, or anything like that. Metallurgy, civil engineering, mathematics.
On the other hand, i've worked with plenty of people with CS degrees from respectable universities who were useless. A degree is not anything like a certificate, and universities simply aren't in the business of actually deeming anyone suitable to hold any software engineering job in the industry.
Even if you fixed this, so that somehow every competent programmer, and only competent programmers, had some certificate from a university, all it would do is let you hire graduate developers easily. It wouldn't let you sort the wheat from the chaff at senior level.