A long explanation can be a way of delaying the moment another person gets to disagree.

As long as you are still explaining, nobody can disagree. The elaboration keeps the floor, forestalls the response, and postpones the moment when your position has to survive contact with someone else’s. It often feels like thoroughness and functions as defence.

Try making your point in three sentences and stopping. The silence afterwards is uncomfortable and it is where the actual conversation starts. If your position is any good it will survive being said briefly.