Worth Acknowledging

I hear the "Manafort and Cohen's crimes had nothing to do with Trump or Russia" defense already. Let's just acknowledge the following (hat tip to Matt Yglesias):

Mueller has a broad but still finite mandate to investigate matters related to Russia’s intervention in the 2016 campaign, Trumpworld figures’ possible involvement in the meddling, and the circumstances surrounding former FBI Director James Comey’s firing.

Mueller used that mandate to successfully prosecute Paul Manafort for crimes that, though related to work for Russia, do not appear to directly relate to the 2016 campaign. The strategy, evidently, is to try to create pressure on Manafort to cooperate with the investigation and implicate others — potentially including Trump.

But unlike former independent counsel Ken Starr (or his former lieutenant and current Supreme Court nominee Brett Kavanaugh), Mueller is not operating as an all-purpose roving anti-Trump ombudsman who just looks under random rocks and tries to find dirt on Trump. Consequently, when he uncovered evidence that looked bad for Cohen but had nothing to do with Russia, he passed it off to ordinary prosecutors. 

 This is an excellent point. Let's not forget that Ken Starr started off investigating a shady land deal in Arkansas and wound up investigating Bill/Monica hanky panky.

As a final note, let's not forget this (in light of the upcoming election):

The key thing to remember about the Russia investigation is it exists not because it’s the only aspect of Trump’s conduct worth investigating, but because it’s the only worthwhile investigation that congressional Republicans were willing to pursue.

Republicans run the House and Senate. The only way that any investigation will ever go anywhere is if congress authorizes it. The reason there is no investigation into Trump's campaign finance, previous business dealings, alleged sexual harassment, etc., is because those controlling congress won't authorize the investigation.