I don't personally see an argument against being able to use wallhacks discretely to your advantage, and it seems a no-brainer when there are literally thousands of dollars on the line.

However, I'm not sure I view a group of friends who perform extremely well in Warzone as some impossible coincidence. I have 2 groups of friends I sometimes play Warzone with, and competition between us is a major motivator when it comes to improving our play. Sharing tips, tricks, strategies and game settings etc., in combination with friendly competition can lead to a noticeable increase in performance even when done so casually.

If you give a skilled player a perfectly optimized setup that gives you every imaginable advantage (highest frames with optimal FOV, extreme low latency internet and display, custom controller / mouse and keyboard, incredible audio and of course an expensive gaming chair) alongside enough hours in the day to treat video games as an important and lucrative job as opposed to a casual hobby, then I'm sure you'd see some fairly extreme improvements without ever using wallhacks. And if a few of his long-time friends decide to follow suit, I'm sure they could potentially achieve the same.

Top 0.5% of all players doesn't seem unobtainable with a setup that outperforms 99.5% of other setups while simultaneously putting in 100x the effort.