You hit on the key word - "dysfunction" - it is unlikely that any major policy changes impacting business will make it through Congress. This includes tax policy, immigration (H1-B changes), or anything else. From a business perspective this eliminates uncertainty in planning. From a political perspective it simply serves to demonstrate that the current crowd in Washington are idiots.
But you talked about uncertainty, given Congress is still trying to pass ACA repeal and Trump keeps threatening to damage it using executive powers, that's a huge amount of uncertainty hanging over the economy. Same with tax reform which may or may not pass.