After Trump became POTUS, he knew that there were too many dems, and dem sympathizers including RINOs, in the DOJ etc. to prosecute the scoundrels. (BTW, to replace a disloyal DOJ character, a new one has to be confirmed in the senate, and why would the senate want to do that?) TDS nuts here on FR criticize Trump all the time for not “cleaning the swamp.”
I suspect The Founders believed Impeachment was a preferable end to a Presidency than an armed duel (or, in the case of Democrats, to assassination).