Wouldn't the overlap between “people who run OpenWRT” and “people who use EOL D-Link routers” be "people who run OpenWRT on EOL D-Link routers"? The table of supported hardware at the OpenWRT site lists several D-Link models which can run the latest OpenWRT release, and several of them are marked as "discontinued" (that is, no longer sold), a few of them even being in that status for more than five years.

I don't know, I've installed openwrt on each device I've owned especially because their original firmware wasn't supported anymore (or crap to begin with).

Often because the cheap devices were either all I could afford or because I've even gotten them for free or basically free, like on flea markets.