The signature complaint is downright stupid. They verify the sigatures BEFORE they open the ballot. They are not even going to open and count the votes on the ballot until the affidavit (ballot envelope) is approved. Otherwise election officials could see your votes influencing them to either accept or reject your ballot.
The signature not matching what they have on file also doesn't immediately disqualify your ballots. They will flag it and set it aside. How it is dealt with then varies a lot which has brought up another absurd technical controversy.
Many states allow you "cure" your ballot. Say the signature doesn't match or you didn't sign it or didn't print your address on the envelope or you used a preprinted address label.
The GOP has fought over every one of these, Right now Trump is trying to throw out almost 700,000 votes in heavily Democratic areas because the State allowed counties to identify flagged ballots so they could be cured. Some did, some didn't.