John Gruber in response to this from me:
I’ve never used WordPress, so obviously I’m no expert on administering it, but if a smart guy like Dr. Drang has enough trouble getting it to run smoothly with caching that he goes back to running it uncached, I’m going to go out on a limb and say it’s not easy.
I don’t know what problems Dr. Drang was having in particular, but I do know one thing: WP caching is problematic on certain webservers.
It is not, however, hard to implement.
WP Supercache, for instance, is very robust and only takes a few clicks to get up an running — again certain servers don’t play nicely with it. Ideally WordPress would build in a static generator or caching mechanism, but Automattic has indicated that they have no interest in doing so.
(Side note: I don’t know if Dr. Drang turned back on caching, but his site seems to be mostly staying up.)