That is why many do not come here. They can not defend their positions with logic, facts, nor evidence. Orange man bad! Why? Where are the facts and evidence? Crickets.
If by "here" you mean PilotSpin, then I take issue with that logic. While I agree that many liberal positions are very hard to defend, especially on government run anything (the creep towards socialism), I think that if you start out by saying that liberal positions can't be defended, then there's no reason to even discuss it with you. After all, no matter what is said, nothing will be acceptable.
The reason we don't have many liberals here isn't because they can't defend their positions, it's because of how they're usually treated by a select few. The treatment part aside, why would they want to try and discuss their viewpoints when they won't be accepted by anyone to begin with? That seems to limit the ability to debate, I would think.