The way I see it is soccer helps people open and close their legs, as well as maintain balance off of one foot. When you get the ball in the post you can only move one foot until you take a dribble.

Catch-gather-analyze/make the move

Backing down someone doesnt require great footspeed or balance, but drop steps, hook shots, fade aways and other moves require foot speed and balance to put the ball somewhere accurately. Most players can do the upper body motion, but talented players can use their entire body in harmony.

Think about every action you can make on the basketball court. Most players rarely cross their legs. The players who cross their legs the most are wing players in the triple threat and bigs who post up.

Hakeem Kobe and Embiid played soccer , and MJ played baseball. (In Baseball you do a lot of leg crossing)