The thing is, depth discussions have been going on for decades and these swimmers literally live in the pool. When people spend literally 40+ hours a week in water I trust them well before I trust scientists because it takes scientists so much longer to catch up and measure what the practitioners are observing.
Like this reminds me of Beckham/Ronaldo doing free kicks. They had a deep understanding of controlling the ball well beyond what scientists knew how to measure and explain what they're doing.