Until there is a viable third party in US politics, is there anything to fret over?

With this entire sniveling, griping, etc. it is to no avail unless if there is no viable third party to play spoiler. If Trump gets in the White House, unless the party of Twiddle Dumb controls both the House and the Senate Trump will get nothing done because the party of Twiddle Dee will stonewall him, and vice versa if Hilary gets in, the party of Twiddle Dumb will stonewall her. The stalemate always favors the ”No” party, even without a vote being decided on any issue. Why worry about a candidate that doesn’t control both houses? There is nothing really that will be a game changer until a candidate appears to have both the House and the Senate on their side. The only way none of that would factor is if there were a third party large enough that they would be needed to push anything through.