I think if someone is so good that the obstacle between them and a world record (or even placing in the top X%) is just a piece of gear, then they are likely to

I think if someone is so good that the obstacle between them and a world record (or even placing in the top X%) is just a piece of gear, then they are likely to be sponsored. That calculus is easy for the shoe manufacturers. If you can give someone a pair of shoes, and have them perform in the top 10% of every athlete in that sport, you do that all day. Where that cutoff point is is kind of up to the manufacturer. Unfortunately, there will always be people on the bubble, whether it's from an equipment affordability perspective, or performance. It's still true with your solution. Additionally, the more rules you impose, the weirder shoe manufacturer behavior gets.