This presupposes that the llm will be able to pick up the slack for the users of imprecise language as to me that is a proxy for domain expertise. If so then the human is not needed which does seem like a stretch.
I have not come across a rigorously argued technical analysis that has claimed that using precise language can in any way eliminate the possibility of hallucinations or unaligned behavior. Short of providing a proof for the elimination of hallucinations and confabulations, merely reducing the behavior by a random percentage is not an acceptable status quo for completely removing the human.
It requires that LLMs are equally effective with imprecise language as precise language.
And while I'm sure the frontier labs are continually iterating on 'garbage in, something vaguely useful out', it's a high bar to get that output to be as useful as if it were more precisely prompted.