"Somewhere along the way [libertarianism] morphed into some creepy philosophy based on a novel by Ayn Rand"
I don't know that libertarianism ever made much sense really, but the idea that the government that governs best governs least has been a guiding principle that Americans have applied to their political philosophies for a long time. Even we liberals tend to think that there are times, as in the case of making marijuana illegal, where too much government activism isn't a good thing.
Unfortunately, applying that idea as some form of absolute, and particularly saying that the government has no business regulating a magical fairyland called "the free market" is complete nonsense. When the marketplace can't take care of something vital in our lives like health care, then using the government to fix it is not only OK, it's quite often essential. Markets don't fix themselves. That's particularly true of markets where there are economies of scale, because it is quite often the most ruthless people who end up running them.
"Libertarians also hate Medicare and Social Security, and there are problems with those programs, but .. it beats stepping over lepers and watching human skeletons shit in the river, and I also like not seeing those things. I'm selfish that way."
As far as I'm concerned, liberalism (or socialism, if it goes a little further) makes sense from a selfish perspective as well as from a humane one, as Maher alludes in that quote. When the world around us is full of safe, healthy, and secure people it's a better place than when it isn't. I sometimes wonder if most Americans will ever grapple with that notion, let alone embrace it.
For that, and many other reasons, libertarianism justly deserves this smackdown. It really is the province of people who have never had reason to find out how arbitrary and capricious life can be. In other words, it's for people who have yet to grow up, in at least some sense of that phrase.