Back in the day, TT, and a few others were heavy into multi-rail power distribution which turned out to be yet another marketing blunder. The theory "sounded" good. If one rail failed the other still provided power. Plus, the sales pitch claimed if one rail failed catastrophically, the components on the other rail would be protected from possible damage.
But what good is power to the graphics card if power to other major components on the motherboard died? Plus it meant the supply always had to keep in reserve, some power for each rail - effectively limiting available power where it might be needed. And multi-rail designs are more complex with more components, thus adding to the cost with more potential points of failure.
While it certainly is possible for a PSU to fail catastrophically and take out everything connected to it, that is extremely rare these days. This is especially so when you stick to the name brands as nearly every 1/2-way decent supply has excellent protection circuits designed specifically to cut output when any significant anomaly is detected.
Be quiet! still sells several multi-rail models claiming multiple small rails result in quieter operation. But frankly, with a bit of homework, finding a very quiet (or even silent - at least most of the time) single rail PSU from a quality maker is not hard to find.
