There's also no need to get a real id drivers license in that case except for convenience and reduced risk of losing the passport, since every identity verification circumstance which restricts allowable drivers licenses to the real id version also allows a passport.

You're totally right that drivers license and passport ought to be sufficient documentation to get a real id, at least for US passport holders or for foreign passport holders when suitable evidence of lawful status is physically present within their passport. But that's not how the real id rules are written, since two proofs of the address of residence are also required. Not all non-real id drivers licenses prove residence (as opposed to for example mailing address), and at most, driver's license plus passport will provide one such proof and not two.

Documentation of the Social Security number, such as a Social Security card, also used to be federally required. Although this requirement was removed, nothing forced the states to remove the corresponding requirement in their own state-law rules, and some states still retain that requirement. Providing any Social Security number you have been assigned is still federally required, and the number is still verified against SSA records, but the feds no longer require the applicant to provide proof that it's their number.