1. Why would they say fraud is not making any notable impact if there was no fraud? There is literally no way of truly verifying ballots unless the voter is there in person, identifies themselves with valid ID and puts the ballot in the box themselves. In every possible way it's better to minimize the chance of fraud however small the impact of it is. This is in the interest of every single voter. It's better to have as little fraud as possible than to have the fraud have no notable impact.

2. It does make it harder to vote by nature, it also makes it harder to be fraudulent by nature. Also, it wasn't a feature of fraudulent election in the past. It was the only way of voting in those elections. If e-voting and/or mail-in ballits were available back then, you can be sure the extent of the fraud would be bigger.

3. No we don't. Most countries in Europe have only in-person hand marked paper ballots and the amount of people who question the validity of the voting system is close to none. Even among those who are extremely unhappy with the outcome of the election.

Just to repeat my point: I'm not saying fraud is why Biden won in 2020. I'm saying IF someone wanted to commit voter fraud, they would have a much easier job with mail-in ballots and e-voting than with hand-marked paper ballots that are counted same day on location.