Fully heat treated tubing is a rarity in steel bikes, the whole bike needs to be heat treated as a whole, or you get serious heat affected zones where the heat is used in joinery. Or you get some bike tubes that are designed for welding where the heat affected zones harden, which is OK, kinda random. Or you get 4130 type tubes as per LHT, and the tubing is semi hard.

Quality Al frames are fully heat treated.