I recently asking about getting a frame that had been powder-coated chased and faced. The guy seemed to think the same, he said he would chase the threads, but thought facing the shell was a bit unneccessary with a modern bb system
That's exactly the wrong way round - an older cartridge style BB is generally ok with that sort of treatment, a modern external, twin-shell design needs both faces against which it aligns to be parallel with one another.
I recently asking about getting a frame that had been powder-coated chased and faced. The guy seemed to think the same, he said he would chase the threads, but thought facing the shell was a bit unneccessary with a modern bb system