Short-Term:
Other positions in the NBA, mainly power forwards and centers, were more dominant than guards
“Successful NBA franchises for fifty years relied on the team's dominating centers, who were usually the first draft choices…” (Nourayi).
This is good evidence as it shows teams relied on their big more significant positions to score and that's why they were mainly the first positions drafted. This tradition was normal for around 50 years until Magic.
Long-Term:
Teams were more focused on rebounding before Magic Johnson came into the league. Rebound numbers drop from there on out when he got into the league.
"So many more shots meant so many more rebounds, especially when combined with factor no. 2 in Wilt's favor versus "Drummond: Teams in 2019 don't miss enough shots," (Kram).
Wilt Chamberlain’s time had inflated rebounds, because players took more shots and made a smaller percentage of them than players did in and after Magic’s time. Inflated rebounds (above average rebounds compared to today) were the largest part of NBA stats from the start of the league in 1949, to 1979 when Magic was drafted. Magic coming into the league changed the course downward of how many rebounds a game teams in the league would have.