Sure. What I mean is, they'll whine to you anyway, trying to get around the system. And, practically, refusing to talk to them is difficult-to-impossible.

I'm not sure that it should be the professor's job to handle appeals. It should be the same sort of process that schools use to handle appeals for missed tests and work.

You miss a test, you get a zero. You go to the office of the dean with a note or explanation, get them to sign off that you should be allowed to retake, reweight, or whatever else it is that is needed, and then you go to the professor to deal with it.

The same sort of process should probably be put in place for plagarism. The professor flags you, and if you want to appeal, you go to the dean's office, they review the possibly-plagarized paper, and if they feel that the professor was in error, or that the student deserves the benefit of the doubt, they allow some sort of corrective action.

It shouldn't be their job at all, I agree, but the practical consideration is that they'll have a line of complaining students in their office that they can't exactly get rid of.