Isn't this about applying for a green card directly from a non-immigrant visa, e.g. student? H1-B is an immigrant visa.

H1-B is defined as “non-immigrant.” https://en.wikipedia.org/wiki/H-1B_visa

> H1-B is an immigrant visa.

I don't believe that's correct. H1-B is formally a temporary, nonimmigrant work visa/status which permits "dual-intent" (meaning a holder can be openly seeking permanent residence when applying for [or when on] such a visa without that dual intent being immigration fraud).