There needs to be a balance between tech and natural ability, and right now things are tipping more to the tech side. If a shoe has the ability to give you a 4 percent advantage over another with the same running ability, then that’s cheating.
“Instead, the analysis suggests that, in a race between two marathoners of the same ability, a runner wearing Vaporflys would have a real advantage over a competitor not wearing them.”
Kipchoge ran a sub 2 hour marathon in them, but prior to that his time was 2:03! He picked up a whole 3 mins from that shoe, when an increase in ability and time are based on a few seconds! Runners don’t get better bun minutes once they are in their prime.
If you can’t do it without the shoe, then it is not natural or real.