I never claimed it did.Also, it says nothing about "stopping at 0". I've never even heard of the idea before this thread.
As you say, DMG took precedence over PHB when they differed. We never saw that piece of Sage Advice, but then we seldom read Sage Advice. Maybe it was later changed to be optional, but my point was just that 1e AD&D had a rule (at least for some time) that you were still alive at 0 hit points.Now, rules in the 1e DMG do take precedence over the PH, but IIRC the question was addressed in either a Sage Advice or From the Sorcerer's Scroll article back in the day and the DMG rule was called out as optional.