They need to know what the margin of fraud is at midnight on Election Day. Bye-den “banking” more votes by that time gives them more precision in the number of ballots they’ll have to stuff +14 days later.
I think there are two reasons for the pivot. 1) It’s not as easy to manufacture fraudulent ballots as we all here suspect it is. All there hard-core lawbreakers are out filling up on free stuff. 2) The polls are tightening, and if that trend continues, they might not be able to produce enough, anyway.
If Trump wins in a landslide on election night because all the Dems withheld their votes to be mailed in, no one will believe that many people voted by mail. If they go to the polls and vote after mailing their ballots...it’s still fraudulent because ‘rats are voting twice, but IMO it will look “believable” from a percentage standpoint.