Conservative groups influential with the Trump administration have pressed for the preemptive acts of clemency.
There’s a world of difference between a pardon issues to prevent malicious prosecution for non-crimew and one issued to people you’ve been instructing to commit crimes



You are in error. Nixon was pardoned by Ford for any and all crimes he may have committed in office. Carter issued a blanket pardon for all Vietnam draft dodgers whether charged or not. There is nothing in the constitution or court rulings that blocks a preemptive pardon.
The only rule, from an 1866 SCOTUS ruling is that the pardon must come after the crime, whether there have been charges or not.
Edit to add: Trump’s pardon of the Jan-6ers included a preemptive pardon for all those that had not been charged yet.