this only make sense if we also remove 'is he stealing american job' verification step (LCA) for h1b.
otherwise its just weird to do you bunch of checks for h1 candidate and not do any checks for the spouse when they are potentially doing the same job. If someone is working on h4 then they should be able to get own h1b otherwise they are "stealing an american job" by definition.
Well that's the way green cards work. Only one spouse needs to pass the Labor Certification (LC) but both spouses get green cards and can work any job.
The H4 work permission was basically a stopgap for Indian citizens who should have gotten green cards years ago but didn't because of processing backlogs.