Freddie Freeman has 69 RBI this year. If he'd been batting 8th all year he'd have a lot fewer than 69 RBI. If he'd been batting leadoff he'd have a lot fewer than 69 RBI. If he'd been playing on a team where literally no one else got on base, he'd have 18 RBI.
If RBI were a good indicator of how good Freddie Freeman is at hitting, it would mean he was somehow worse at hitting when he hit leadoff or 8th or surrounded by terrible hitters. That doesn't make much sense, does it?
Edit: To go back to the Ozzie/Baez example: Baez has 84 RBI on the year to Ozzie's 59. If RBI are an important measure of a hitter's ability, that would seem to mean Baez is a better hitter than Ozzie. But Baez is batting cleanup with Anthony Rizzo, Ben Zobrist and Jason Heyward (three guys who are exceptionally good at getting on base) in front of him; Ozzie bats second and has the 8-spot, pitcher spot, and for much of the year a struggling Ender Inciarte up in front of him. The consquence of this is that Baez has come to the plate with runners on base 217 times this season, Ozzie has only done it 148 times. Why are Baez' 69 extra plate appearances with men on being held against Ozzie in this comparison?