Honestly, when it comes to guilt without any reasonable doubt, he has to investigate every stone, before he can make a move, or he'd be the fool.
Everything we see on the surface about all of Trump's criminal activity, along with his co-conspirators, is abundantly obvious. But what we didn't know, until recently, that Ginni Thomas has been implicated. All leads have to be investigated to make sure everyone is held accountable. And as we have seen, that list keeps growing.
I'm no different than you, and I am extremely confident we have enough evidence now to convict them all. But, do we have all of them is the question?
I think in the very near future, Garland is going to drop a daisy cutter on this whole investigation, and it won't look good for any of them.