The main issue I see here is that EA made a deal with a competing vendor for DLC exclusivity (outside of Origin).
If EA had the DLC available in Steam as well, none of this would be an issue.
As for BF3, I'll wait to see what happens. The comments that started this thread were from GameStop, whom has nothing to lose by bad mouthing Steam, and only potential sales to be gained by getting inaccurate info out there suggesting BF3 won't be on Steam.