used office (thin-)clients make much, much beefier routers and mediacenters without using more power (thou some have fans running at idle load) and costing less.
They are indeed reasonably good for things where it doesn't really matter if it falls down, but I'd be laughed out of the room if I suggested we built a business on top of second-hand thin clients, doubly so when I turned up to a client site carrying on with two USB ethernet adapters and a USB LTE modem hanging off the back to put in a machine room.
used office (thin-)clients make much, much beefier routers and mediacenters without using more power (thou some have fans running at idle load) and costing less.