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
According to Associate Justice Joseph McKenna, writing the majority opinion in the U.S. Supreme Court case Burdick v. United States, a pardon is “an imputation of guilt and acceptance of a confession of it.”
According to US legal precedent a pardon carries with it the implication that you are guilty, and can therefore be refused to allow an innocent conviction. Skipping the trial also skips the presumption of innocence.