The Time Lords didn't create the Time Vortex, it is a natural thing. The Time Lords simply learned how to travel through it. The Reapers are also natural. The idea that the Time Lords created the Vortex comes from one single novel and conflicts with what's been said in the TV show. It especially conflicts with the notion (most clearly expressed in "A Good Man Goes to War" but hinted at earlier) that exposure to the Vortex was part of what turned them into Time Lords, in the first place.