Also @Ristamar. At first I felt the same way. The reason I came to believe that RAW entails otherwise is the wording "If you take any damage while you have 0 hit points, you suffer a death saving throw failure." It is clear that the missiles hit simultaneously, so if I ask the question "How many missiles caused damage while the character had 0 hit points remaining?" The answer is "None! The missiles all hit simultaneously, while the character had positive hit points remaining."
For a cast of the spell whose missiles hit a character simultaneously at a time when that character is already at 0 hit points, the situation is different. The missiles still hit simultaneously, still deal damage separately, but now they satisfy the RAW "while you have 0 hit points".
Taken together, those accurately satisfy both the RAW and the related Sage Advice. A hesitation is that it might seem more intuitive to treat the missiles as dealing damage one at a time... which has been clarified as not being the case: they're separate but simultaneous.
I had considered that argument, though I could not logically reconcile why the missiles would force multiple Concentration checks yet only a single death save when both conditions involve simultaneous yet separate damage.
That being said, I wouldn't begrudge a DM for handling Magic Missile with either method as long as it's consistent.