Nah its fine you and me are both right in our own ways. Powerlifters go for absolute maximum, but just below them are bodybuilders. You won't get huge muscles by doing tons of relatively mild repetitions, it just doesn't work that way (say 15 reps of medium effort vs 3-5 of max you can do, former gets you endurance and tonality, latter volume).
Ie Arnold was doing 550 pound (250kg) squats at some point, thats not something you will ever see in normal gym. Similar for other exercises.
It is true that high reps/low weight will build more muscle endurance, but less strength.
However, it is a myth that it results in more "tonality".
Muscle definition is only a result of muscle size and body fat percentage. So you can achieve just as much muscle definition doing high weight low rep exercises, all else being equal.
Ie Arnold was doing 550 pound (250kg) squats at some point, thats not something you will ever see in normal gym. Similar for other exercises.