Because H1B is for skilled "workers". Not necessarily someone with 10yrs of industry experience.
There are a lot of 22-24yr olds who start their professional careers on the work visa. H1B is the only work visa that you can get with relative ease after studying in the US. The other work visas are an even bigger mess.
Unless you are saying that anyone coming to study in US colleges for undergraduate programs should not look for a job here because the US only hires "skilled migrants"...
If H1B is for skilled migrants then why would college graduates by applying?