The success of Scott Alexander (AKA Scott Siskind) seems unlikely. He’s done everything we’re told you shouldn’t do when writing on the internet. His essays are frighteningly long. His language is not simple. And he doesn’t have a personal brand, exactly. He does cluster around a few subjects repeatedly—psychiatry and political philosophy, for example—but he also does whatever the fuck he wants to. When his whim dictates, he’ll pen surreal stories about psychedelic cacti, dole out ad…