An Experiment in Scotch

I’ve decided that peo­ple on the Inter­web are all idiots and morons and that peo­ple should really just agree with what­ever I say and we’d all be happier.  Is that so hard to understand?

More seri­ously, why is it so dif­fi­cult to have an intel­li­gent con­ver­sa­tion with peo­ple on the web?  What about human nature makes ad-hominem attacks com­pletely accept­able in a com­ment thread?  I know there have been stud­ies on this and the lack of empa­thy with a face­less oppo­nent but it still bugs me.  Have the decency to assume intelligence.