This is actually a good point. AA has pivoted away from high volume corporate travel. A lot of smaller unmanaged companies (like the one I work for) actually have far less restrictive travel policies. We are basically allowed to book whatever we want, as long as it is reasonable (ie a roughly $200 OW fare difference to fly a preferred carrier would not be challenged).
I can't find an AA fare within $200 range of WN or DL, so I'm making elite status with both WN and DL, I'll finish the year out as PLT on DL and A-List preferred on WN. The fare difference in usually $300+ on AA.