If I read this correctly the gist is that it does not matter if you use heavy weights with few reps (common body builder wisdom) or lighter weights with more reps. As long as you always exercise to complete muscle fatigue you'll get the maximum for your genetics (which itself varies a lot).
It’s worth noting that muscle is not all the same. If you’re just into bodybuilding then sure, proximity to failure is what matters. For athletics though, there still seems to be a big impact in the rep range you work in.
All of these benefit from weight training, but depending on the sport, the programming will be very different.