I'd disagree with the more global point (in the title) that tmpfs is harmful: it's actually quite handy for all sorts of things. As an amusing example, the SHM

I'd disagree with the more global point (in the title) that tmpfs is harmful: it's actually quite handy for all sorts of things. As an amusing example, the SHM (shared memory) system in linux is actually implemented on top of tmpfs (/dev/shm is a tmpfs mount). Other uses include CoW shadow mounting (when unioned to an immutable filesystem). That said, the point that /tmp should not be a tmpfs mount is actually a decent one, just because we're used to the idea that /tmp is neither space-constrained (it's scratch space) nor extra performant.