I have lived in two states that allowed mail in voting and I never felt my vote was not counted. I disagree with the anti-mail in vote nonsense. That is just another conspiracy theory that does no one any good.
I agree as well and I think it cost Trump votes in 2020 when he discouraged mail-in voting in the middle of a pandemic.
There will always be people who have every intention of going to the polls on Election Day and then for whatever reason, just don't make it.
Democrats, on the other hand, were like, "Vote by mail! It's so easy!" And people did.