Why Presidents Prefer Not to Investigate Former Presidents

"President-elect Joe Biden has privately told advisers that he doesn't want his presidency to be consumed by investigations of his predecessor," NBC News reports (claiming five unnamed sources). Supposed reasons:

1. "concerns that investigations would further divide a country he is trying to unite and risk making every day of his presidency about Trump"
2. "he 'just wants to move on.'"
3. He "wants his Justice Department to function independently from the White House."

Well, maybe those are among his reasons. But there are other good reasons for any president to not want to persecute his or her predecessor.

One is fear of your successor doing unto you as you have done unto your predecessor. Political rivalries being what they are, if sitting presidents start investigating past presidents, they'll find themselves investigated in turn.

Another is fear of finding one's own power constrained while in office. If Trump is successfully prosecuted for something he did while in office, Biden and other future presidents will be less likely to get away with doing similar things while in office. And presidents hate any limits on doing whatever they damn well please.