“A Tacx Vortex can produce 950W max power where as the Flux will give 1500W, is the Vortex rider at a disadvantage if he or she can output more than 950W?”
If he or she is routinely putting out > 950W, he or she should have chosen a different trainer!
That said, the number of riders sustaining that level of output for anything longer than a sprint is likely quite small. At a high level, sure - it seems a virtual race *could* be won or lost in a sprint for the line between two equally fit riders if both are capable of, say, 1200 W max - and one has a trainer good for only 950W while the other tops out at 1500 or 2000W. But the number of instances where this happens is probably pretty low (mostly because people churning out 1000W or better already *know that they can* when choosing their trainer, so the fastest of the fast are already competing on a more level playing field).
In any case, how would Zwift ‘normalize’ that? The only feasible way to do so would be to apply a wattage ‘cap’ to all racers based on the max resistance of the least capable trainer entered in a given event… and that would be absurd, don’t you think?