Actually, I thought about it some more. I think a server that spends 99% of its time blocked on IO is "IO bound" even if it's because no one is sending it requests. It's a very different condition than saturating the NIC, but it's still meaningfully waiting on IO. Like, the process has to be spending its time somewhere, and it doesn't know "why" it's blocked.

Maybe the terminology around this could be developed some more.