The FBI "did not establish" that Al Capone had people killed. The court of law "did not establish" that OJ Simpson murdered his ex wife and her friend. Yet they very clearly did those things.
The issue I see with your assertion is that we know from past presidential scandals how enormously difficult it is to elucidate criminal activity; it took years before the Watergate investigations finally uncovered enough evidence to expose Nixon's crimes, and Reagan served a full eight years in spite of his illegal involvement in the Iran-Contra Affair. Yet despite the contents of the Mueller Report, we have a large portion of the citizenry (most of whom haven't even read it) who are already certain that Trump is innocent, after only two years of investigation. The citizenry was certain of Nixon's innocence after two years of Watergate as well; they "did not establish" that he had committed any crimes at that time. But he clearly did.
It appears that you need to be convinced that a crime was not committed. That you have the presumption of guilt and you will stick with that because in your gut you feel like he must have been complicit in the election meddling.
I take the opposite approach. I need to see evidence that the Trump Campaign actually conspired or coordinated with Russia before I will believe or assume that they did.
I also take the position that this accusation was politically motivated from the very start, and has no evidentiary basis. That illegal warrants, illegal leaks, and slanted and straight up false reporting were used in furtherance of those same political goals. And all this makes me doubly determined not to accept anything but evidence before entertaining the notion that there was collusion or coordination or cooperation.
I am definitely not certain that Trump did not collude with Russia. What I am certain of is that there was never any direct evidence of collusion, the media and the democrats knew this, and still decided to run with it to drum up ratings and political capital. And in the end using lies to push a narrative, no matter how good the intention, usually blows up in your face, with the crazy Trump now shored up even more for the next election. I really do hope a progressive wins the next democratic primary. Otherwise we are in for another 4 years.
The issue I see with your assertion is that we know from past presidential scandals how enormously difficult it is to elucidate criminal activity; it took years before the Watergate investigations finally uncovered enough evidence to expose Nixon's crimes, and Reagan served a full eight years in spite of his illegal involvement in the Iran-Contra Affair. Yet despite the contents of the Mueller Report, we have a large portion of the citizenry (most of whom haven't even read it) who are already certain that Trump is innocent, after only two years of investigation. The citizenry was certain of Nixon's innocence after two years of Watergate as well; they "did not establish" that he had committed any crimes at that time. But he clearly did.