This is quite independent of the US. The state functions purely to protect the interests of the dominant class. In the US, the dominant class happens to be capital owners, but that's true in most of the world these days.
Multiparty systems can become completely deadlocked as well. Belgium has had complete deadlocks because nobody can form a coalition, Israel had five elections in three years for similar reasons, Britain was effectively deadlocked under Theresa May, and Canada has had outright minority governments.
I also wouldn’t describe US politics as “rigid” just because we have the same two parties, because each party has different factions and some of the most powerful factions were either marginal or completely nonexistent a couple decades ago.
The biggest problem with the U.S. system isn’t that there are only two parties (that’s a problem, just not the biggest one). It’s that both parties need to agree in order to pass anything (due to the senate filibuster), which as far as I know is unique among democracies.
The filibuster is just a product of the Senate rules and could be changed at any time. There's no incentive to do so now because the Democrats currently control the Senate but they couldn't pass anything even without the filibuster because the Republicans control the House. I suspect it's going to happen with the next trifecta.
I'm not saying that to say that the us is any better, but simply for context for what happens when you don't need all the parties to approve:
France effectively has that by way of the infamous 49.3. the majority party coalition can effectively force all others to accept a law, without ever presenting it for a vote.
The caveat is that the other parties can start a vote of no confidence and dissolve the government with a simple majority, but in reality this never happens because dissolving the government over [pension reform, the budget, insert issue here] is disproportionate.
The current government's lack of caring about their voter base because of the Overton windows shifting to the right has obviously aggravated this.
any sentence that starts this way is just walking straight into its own falsity.
No human system as complex as "the state" ever functions "purely" to do anything. Instead, it's a venue in which different interests and power levels sometimes compete and sometimes cooperate, sometimes achieving goals and often not.
I tend to agree, but then I look at Europe and I say, who is the ruling class here? In the US it's obvious that corporations run everything, but that doesn't seem to be the case in western Europe.
I won't say this is a good representation of every european country, but in France, basically two bilionary own all mainstream private press media, the rich class basically built Macron to push their agenda, and most important laws anyway come from Europe transpositions where only those that can build a perpetual lobby service can push a topic into a directive.
So yes obviously Europe is a paradise of direct democracy where every citizen bloom thanks to a social structure made to help each of them thrive and reach the best version of themselves acting everyday for an harmonious society free of any anxiety about future that promise only bright shiny days for the masses and their children.
Is it possible that they pass USB-C charging and data privacy laws in Europe because the companies affected are primarily American companies not European companies?
Likewise, I imagine they pass anti-fossil fuel laws because there aren't really any major fossil fuel producing countries in Europe besides Russia which is both a pariah and the continent's gas station.
Means & motive are still largely governed by whether you own things for a living or work for a living. The pay to exist vs get paid to exist dynamic is alive and well over there and the debates are all quite familiar. After all they invented the rules and we just copy-pasted them with a few small modifications. The ownership class just isn't as dominant as it is in the US at the moment, for better and for worse.
