This 50% isn't compared to the Intel's Xe-graphics CPUs, it's comparing to the old Gen9. There's a huge difference between those two, with the Gen9 having 0,44 TFLOPS and TG ones (Xe-LP) have 2,46TFLOPS (which is about equal to what Apple is using in M1).

It's just that Apple never used the newer CPUs. Maybe that would have spoiled the M1 launch?

I suspect it's a lot "cheaper", so even if M1 just ties Intel performance and is cheaper & quieter & lighter.. it's good for everyone (exept Intel). Current gen of new Apple macbooks are both really good, and a really good bang for the buck.