I don’t disagree with what you wrote.
However, I do think Pelosi is using the Senate rules to her advantage for the reasons you (and mrssmith) spelled out. The Senate won’t take it up until it is formally submitted.
And that is Pelosi’s only advantage. It allows her to drag this out, to do a “rolling impeachment”, it allows her and Schumer to call out McConnell and the Senate, it lets her and the Democrats keep the spotlight and the narrative, and it allows the Democrats to interfere with the 2020 election by putting a new cloud over the Trump presidency.
My thinking is, they think they won the House in 2018 because the Mueller Russia Hoax was a cloud over Trump. So they concocted this Ukraine Hoax and impeachment for the same purposes.
It is only because of the existing rules that she can get away with dragging it out. (And who knows, maybe other political pressures will force her to move). It may be bad precedent to change the rules (though, they have been changed before, and they can be changed again) and I surely understand McConnell’s reluctance to do much. But doing nothing gives Pelosi more power than she deserves.
Of course they can and will vigorously prosecute the case, to the extent they are able. And I don’t argue they manipulate the procedures of the trial. But they do have the Sole Power over the rules and that is where Pelosi is currently playing, and where McConnell can act to take it away from her.
I'm being repetetive here, but I don't see this as a failure of senate rules. If anything, it is absence of hosue rules (and this came up hard in the "rules committee" hearing on impeachment, how biased the house process was).
The DEMs are violating axiomatic norms of conduct. Not the least of which is all the hoaxes, plus the bad faith construction of the July 25th call.
It's akin to blaming the rules for the conduct of criminals. Some people just don;t know how to behave in polite society, and it's a fools errand to try to get good behavior by passing more rules.