Yes, I have 10g over cat5. I don't need it, but I have it.
Ethernet specs are for cabling in dense conduit. Most people don't have dense conduit in their house. Much cable tests better than the rating on the jacket.
I am using 10G over an ~15m 4 twisted pair phone cable (PTT, common in France even decades ago for ISDN, but no cat cable at all) and don't remember seeing a frame lost in quite some years.
Ethernet specs are for cabling in dense conduit. Most people don't have dense conduit in their house. Much cable tests better than the rating on the jacket.