Comment by drdec
I think you are ignoring the advantage for the applicant.
The reduction in what are essentially spam applications means your genuine application will stand out and be more likely to be considered.
Things that help employers find qualified candidates also help those qualified candidates.
I don't fully agree. I agree that helping employers find qualified candidates is good for those candidates, but I don't agree that making applications mail-in only would achieve that end. It doesn't solve a lot of the larger problems when it comes to job applications, and just makes things harder for the applicant.