As brilliant as our forefathers were, I don’t think they ever anticipated a 1-party takeover of all three branches. They gave the people more credit than we deserved.
I agree. The founders figured the people would themselves hold the reins of power; meaning that the people would themselves occupy the offices of power. Even then, the three branches would fight each other, instead of working in cahoots against the freedom of their fellow countrymen.
Now we observe checks and balances in form only, not in substance.
-- They gave the people more credit than we deserved. --
They gave the people of their time a chance to operate and bequeath self-government and freedom to their heirs, which is all that any group of people can do.
The freedom of our forefathers is long lost. We're a self-governing nation in the same way that Europe is, at best.
They didn't anticipate parties at all. At least they made no provisions for them in the Constitution. They spoke derisively of them. But inevitably, they formed them. Federalist and anti-federalists, termed factions, both claiming to be Whigs.