This is a good series that has brought some sanity back to the discussion.
If I had one nitpick it's that I'd say it's progression that is the key. Adding weight to the bar might be the easiest/simplest forms of progression but it's far from the only one.
Take somebody who does a beginner weight program and works up to 185 pounds on the bench press for 3 sets of 5. He's taking 3-5 minutes per set and his form is decent, but far from perfect.
Now, his joints aren't so good or he's worried about ripping the pec from the insertion or whatever. So over the course of months (maybe years) he stays at 185 pounds, but progresses to 4 sets of 8. He tightens up his form and cuts rest periods to 2 minutes between sets.
That guy got bigger in some combination of the chest/anterior delts/triceps without adding weight. These aren't unreasonable or unrealistic parameters either.
If all other factors are equated then of course you'd have to add weight, but why do they have to be equal? There's a good range of rep ranges, set counts, rest time, volumes etc. that are effective for hypertrophy. Also these effects are multiplicative, not additive, so they can account for a good deal of progress in their own right.