Employers don't prefer university graduates because universities offer better vocational training. Universities teach scientific thinking which makes students better employees. Universities don't teach specific skills but they teach the underling principles.
Employers prefer university graduates because they have to pay extra for good people. And if they have to pay extra they want a kind of certificate that it's worth it plus to justify the extra pay in front of other employees. A degree makes all this easier. Yes scientific thinking is nice but what really matters is that this people can deliver a compkex workload at a given date. In the rarest of cases you actually need a researcher and at that point you want someone with a PhD
