Ronnie Coleman famously said everyone wants to be a bodybuilder but nobody wants to lift heavy weights. Coleman was famous for his strength and was a good powerlifter before he ever started bodybuilding. He brought his emphasis on loading into bodybuilding. Many bodybuilders of the past, Arnold included, were strong and trained with heavy weights. There is no doubt that a sufficient amount of loading is necessary to cause muscle growth.
But few rarely question if loading is always what is best for someone, especially if other stimulus like time under tension or more repetitions can provide results. More so, bodybuilding itself should not get caught up in the mindset of powerlifting where moving more weight at all costs is desirable. In fact, bodybuilding should be focused on quality repetitions and progression of either the number of REPETITIONS or controlled loading over time. In some cases, more repetitions and repetitions variations will provide new growth.
The important point to take out of this is that you need to load, but there are other avenues of growth. Don’t get stuck thinking there is only one way to do it.