Are you saying the two parties are equally to blame? It seems to me that one party is trying to turn the US into a dictatorship while the other is trying to prevent that to happen, and failing.
Even though I agree with the points in your second statement, the counterintuitive conclusion is that the Democrats are slightly more to blame because even after realizing that they're in a losing position, that democracy is at stake, that one-party rule is risked, they still fail to want to fix the voting system, preferring instead to risk losing everything forever.
All topics are polarized to the extreme to fit into the 2 party divide. If a third party would emerge it would be slightly closer to one of the poles. Then it would immediately make that side lose even if more people voted for that position. That is because there is no percentage voting but a cascaded threshold voting. Thus, suppressing underdogs is in the interest of both.
Abstract example:
44% vote party A for X
10% vote party B for X
46% vote party C against X
44% + 10% = 54% for X, but 46% is the biggest party so they win
Question is why the Grand Old Party suddenly quit that century old cartel.
We live in an effective oligarchy and that’s the sad truth of things.