bad_luck is arguing two somewhat unrelated points simultaneously.
1) When evaluating a players performance after the fact, how he made his outs doesn't matter.
2) An out is an out, regardless of how it's made.
The first point is mostly true. You can debate whether a guy who strikes out 200 times could have had better stats, but for the most part, no one really looks at how outs were made when evaluating how good a player's season was.
However, this only applies in hindsight, and BL is trying to apply it in the present. You can only know if two outs were equal after they've occurred. If a guy pops out to first in foul territory, that's equal to a K. It doesn't change anything. But while he's still at the plate, putting the ball in play creates a lot more opportunities for getting on base or advancing runners than a strikeout does.