Originally Posted by star_world

UA is much more dependent on connecting traffic at ORD than BA or AA. If a huge portion of your passengers aren't there, operationally it is often better to cancel everything and re-start the next day. UA is operating a schedule today for LHR-ORD that is close to on time, vs. AA with at least an hour's delay on one of their flights (probably due to crew rest after the long outbound delays yesterday).

I think you're missing the essential point here which is that they're operating an airline, whose sole purpose is to carry the most passengers at the highest possible fares. Large-scale cancellations are done for only one* reason, and that is to maximize the overall efficiency of the operation. There isn't some nefarious plan underway that the "press" needs to investigate

* Actually two now - huge per-passenger fines for long ground delays imposed by the US govt. definitely influence decisions on whether or not to cancel flights in severe IRROPS situations.