People win wars... Not equipment.
The British used the Besa machine gun (Czech ZB-53) chambered in 8x57 Mauser during WWII. So by your connotation, 8x57 Mauser won WWII alongside the .303.
I agree with everything you said, the Lee Enfield was the best WW2 sniper rifle. But, the Lee Enfield isn't the most accurate of the three.
The Mauser is the most accurate action but, what failed K98 snipers was wehrmacht policies. The Germans didn't recognizance snipers as tactically essential. The requirements for a sniper rifle were very loose to say the least. At first they took GEW98s that were reworked into the K98 pattern and chose the ones with the best bore condition to be snipers. In 1939 they "tightened" the requirements to include accuracy of 5 shot group of 12cm (4-3/4") at 100m... which isn't that good when you compare it to the British requirement of a 7 shot group inside 5" at 200 yards, and the Russian requirement to shoot 10 shots into 3.5 cm (1.38") at 100m.
K98 - required to shoot 4.75 MOA
No.4 - required to shoot 2.5 MOA
M-N -required to shoot 1.5 MOA
Damn, now I have a hankering for a PU sniper... Why didn't I buy one when they were everywhere for $500