I can't figure out why office chairs run so much more than easy chairs and are so much less-durable.

I got an easy chair quite some years back. I don't think it even ran $300. At some point, I finally managed to muck up the recliner mechanism, but I've probably gone through five office chairs since I got that, some of which cost considerably more than that. The back wouldn't stay up, or the the pneumatic cylinder would fail, or the mesh would weaken and the front of the chair would press up into legs. The office chairs generally didn't have a headrest.

Honestly, given that I don't actually work with paper at my desk, I'd kind of rather have an easy chair with some sort of mounting pole for the monitor and a keyboard/mouse tray.