> The ballots have to be received by the end of the day of election.

The argument here is: why should someone who voted on election day, or even a day or two before have their vote thrown out because their ballot doesnt arrive to be counted until the day after the election?

I think the argument that there is plenty of time is reasonable, but many elections in the US can be very, very close, so it does matter. Throwing out valid ballots that were mailed on or before election day effectively disenfranchises people (keep in mind some people cant go to polls to vote or drop off ballots, and in some places it is illegal to have anyone besides the registered voter drop off the ballot, so it must be mailed).