youre getting too cocky, what works for you may not work for everyone else. You mentioned you competed when you were a teen, muscle memory works, very few untrained individuals will have 405 deadlift in 3 months. Deadlift is a natural exercise for the body utilizing a lot of muscle groups and I really believe it adds back thickness, me and my training partner grew a lot after introducing it. No one argues there are different ways to increase it, including not doing it but instead strengtheting squat muscles, but many people here are bodybuilders who do not do olympic lifts or various specific-weak-muscle-focusing-powerlifting exercises, so deadlift is the optimal choice for them.