Very much agree.
If your bodyweight is increasing and your strength isn't improving, you're probably adding more fat than muscle. For a prime example of this, do a search on this site for "Artem." The kid gained almost 100 pounds of bodyweight in one year, but did not gain nearly as much strength/muscle as he should have (at the end, he still couldn't squat his bodyweight). When he cut back down, he realized it was pretty much all for nothing.
Had he been paying better attention to his training along the way, after month two or so, he should've realized "Oh shit, I'm up 20 pounds on the scale, but my lifts in the gym haven't moved. What should I tweak?"
In most exercises, and in most workouts, you want to use a bit more weight and/or more reps each session. You're not going to add 5, 10, or 20 pounds on every lift in every workout. But most of them, most of the time is a general goal to keep in mind.