From what I've seen so far, if you're not concerned with doing a powerlifting meet, which MANY people are not, then using a marker isn't going to hinder strength or growth.
If growth is a function of progressive overload over time, and there has only been great results in the strength department with a marker/box (Westide, etc.), then as long as you're focusing on meeting your reps, sets, and adding weight when possible, it really seems like growth won't be negatively affected at all. In fact, it seems like it will be positively affected due to the higher likelihood of strength increases, causing more and more progressive overload over time. Seems to make sense to me.