This might be true, if the policies advanced by legislators more-closely reflected what voters want. Instead, we have a bunch of very-popular reforms that never get done for a variety of reasons, but the one-two punch of the two-party system and the Senate filibuster are a big part of why. Though, personally, I'd say our system naturally stabilizing at two parties is the bigger of those two problems—it's the core reason why major legislative bodies in the US can end up maintaining or advancing laws and policy that differ sharply from what a large majority of voters want, session after session. Unfortunately, fixing that would require a bunch of legislators or a bunch of states to vote against their own interests. So, probably not gonna happen, ever.