Also, those mass layoffs you reference are rather recent and doesn't seem to have anything to do with this specific visa system. At the same time, the pool of available people might suddenly exist now, and that means that a company that needs someone with those skills now has a native worker available instead of having to search for people elsewhere. H-1B workers that were laid off have to exit the USA so it's not like they will add to that pool.
That said, it is still possible that those laid off people were selected to let go because their stills aren't as needed as others inside that company (i.e. positions that only exist due to scale). That doesn't mean those people happen to be the ones that you'd need to seek someone else for. Assuming that all tech people have identical skills doesn't help the conversation.
That's always true. You don't need to provide particulars.
Plenty of education and skill in the USA that doesn't have a fitting job (right now) to put that to use.
Say there are 100000 MBA's but you need someone who knows how to run a kubernetes cluster with a custom syscall shim for a modified kernel and there is someone in Norway who knows how to do that. Even combining all those college graduates combined with all their business education wouldn't be useful for such a role, but that Norwegian person would be. But you still want to stop H-1B?