I agree wholeheartedly on your first point, but can't agree that there's zero evidence of what you said. We do seem to agree that TASS's observation was really them.

I think there are some metrics we can keep an eye on to know if Russia's claims here are true (which is hardly a given!). If it's true their motivations are clear, but there's also a motivation to make a real mess of things while both sides of the aisle fight each other as hard as feasible. Namely, if they can crash America, then America can be made poorer than Russia, and the balance of power shifts quite a lot.

For that reason, I feel like there's a motive for Russia to have done this, and I can't agree with your assertion that there's no evidence Russia ever helped Trump. I suggest that instead, both parties in the USA had reason to not publicize that reality, because it was embarrassing to them. Not even the right wing want to think they were doing the whole thing not to make America great, but to break it beyond repair. They (and we) live here.

Also, I know from working for Bernie Sanders in 2015 that the Democratic establishment is not eager to be directed by the grass roots, or to admit fault or misrepresentation on their part. I don't believe they would be eager to reveal how deep the rot went, and this reticence might have done us a great deal of harm.