I agree and disagree. I’ve been training for more than 30 years. As a competitive and champion powerlifter I know negatives are one component of training but not a primary or very effective method in building power and strength. Slow eccentric work should be used sparingly. Rather controlled eccentric lifting that is not slow but not jerky or too fast. Muscles respond better to explosive training but not bouncy uncontrolled movements. Many more factors go into strength and power building. Rest times between sets matters immensely. ATP needs time to replenish. Rep counts is extremely important as is exercise selection and variation. Slow eccentric lifting is a limited choice for building strength and power and time and time again is shown to be a weak choice for regular training. It sounds new but it’s not.