For every 1 LLM applicant that this idea would deter, you would also deter 50 humans who simply don't feel like having to send a letter to apply to a job.
At least for me, I'd still rather mail a letter versus input all my personal details and job experience into yet another CRM with a crappy data entry interface.
But surely there’s also a downside somewhere.
Valid point if your ratio is correct, but I suspect it's the other way around.