Hiltz
Built for comfort
so lets say a 1st baseman has their foot on the base to field a ground ball from 2nd/3rd/SS, it's on part of the base like the picture posted earlier. the batter/runner steps on the foot instead of the rest of the base that is open. there is no part of the fielder's body that is blocking the batter/runner's path to the base. you know like 99% of plays at 1st base. even if you assume the batter/runner didn't touch the base at all. are you calling obstruction?
No.
The only time I would consider obstruction would be if the fielder's foot completely covered the edge of the base that the runner was trying to access. Which would be nearly impossible.