I think this is a meaningful driver of AA's F fares. I haven't done the analysis recently, but I'm sure that AA's FC seats as a % of total seats across the narrowbody fleet is quite a bit lower than UA/DL (it's not just the 319s, their 320s have 25% fewer F seats than the competition too, and aren't the 321's only 16F (DL is 20)?
Also, FWIW, I suspect that $3k SFO-DAY fare is because of married segment availability that's only offering full J.