2013 MLB Team Correlations w/Runners On:
BA to Runs Scored: 0.829
OBP to Runs Scored: 0.894
SLG to Runs Scored: 0.883
OPS to Runs Scored: 0.935
Batting Average is thumped by both OBP and Slugging Percentage, and (of course) OPS.
And, yes, we know that Hits have more value than Walks. No one has ever stated otherwise. What you haven't stated is that all non-Out events lead to more Runs scored; which is why OBP is actually more informative than Batting Average about who is more productive (and why). SLG is more informative than BA because, unlike a simple ratio of Hits to AB, Slugging Percentage cares about how many bases are actually acquired; which also leads to more runs scoring.
Atomic may have been a bit strong in his rebuke, but he wasn't wrong.