Excellent article on the difference between proper loading of a muscle(s) and simply becoming proficient at lifting a heavier weight.
To sum up the article as succinctly as possible, load is treated as one piece of the puzzle (rather than the whole picture) when trying to induce hypertrophy. Essentially, what bodybuilders have "known" all along about lifting, but have never described effectively (other than with terms that have come to be made fun of, i.e. "mind-muscle connection", etc).
For those of you who have hit a plateau, this introduces the idea that perhaps a preoccupation with achieving a certain weight or number of reps is actually hurting your efforts.