Sorry for not answering earlier. The issue in my opinion has always been that there's only one skill needed to guard the perimeter, yet that skill affects both outside shooting and offensive flow. By contrast, two skills are need to guard inside and both combined only affect inside scoring.
So managers naturally gravitate towards defensive minded guards and wings, but take a more offensive approach to bigs, due to the GE and salary formula making those player building strategies work. This usually leads to the scoring leaders being mostly big men, with the exception of teams that run the Patient aka Kobe offence.