Just a data point from an AA PLT.
Was scheduled BWI-DFW on 12/22, 6:10 p.m. Missed bag-drop deadline by a few minutes, went to agent at priority desk. All flights were F0Y0 (and of course E0) but possible routings to get out that night were BWI-CLT-DFW, BWI-ORD-DFW, and BWI-PHX-DFW, in order of departure time from BWI. CLT was the least promising (oversold etc.), so I asked to be listed standby on BWI-ORD.
Agent tapped some keys and said "sorry it has to be a nonstop for a nonstop, do you want to stand by on the first nonstop in the morning?" I ask her if there's anything she can do, etc., she calls a guy over from a nearby desk, he says "well it can be connecting as long as it's a valid routing, but you can't overshoot the hub so PHX is out--but ORD is fine." So he taps a couple of keys and we're listed on BWI-ORD.
Unfortunately BWI-ORD is oversold, they ask for one volunteer and get one but he waits to see if he'll make it, there's one checked-in passenger who doesn't make it, volunteer gets back on flight, and we don't clear (we were #1 and #2 of many).
I then ask to be listed on the BWI-PHX flight. She says that would be fine (but cautions us that PHX-DFW, a 1 a.m. redeye, is oversold and we risk overnighting in PHX), but then says that BWI-PHX is so oversold that there's no chance of making it, it's running late so there isn't much risk of pax missing their flight, and that the agents there aren't letting anyone else stand by on the flight (this I found odd--presumably *someone* has at least a slight chance of making it if enough pax decide to stay in BWI rather than go to PHX and miss a connection).
The agent then looks at other flights. She says nothing is confirmable "for the $75 per person same day flight change fee" (her words, unprompted by me) from BWI the next day (indeed everything was E0 and most things were F0Y0, the rest being F1Y0 or F0Y1). I ask about DCA, IAD, she says no, I ask about PHL and she says "yes, I can confirm you on the 3:35 p.m. flight and then you can stand by on the 5:00 a.m. -- want to do that?" I say yes, she takes my Amex, charges $75 x 2, and prints us boarding passes for AA2316 from PHL the next day. We promptly drive to PHL, do a park-and-fly at the airport Sheraton, sleep a few hours, and easily clear the 5 a.m. flight (6 or 7 cleared).
tl;dr -- No irrops, missed my flight, airport agent offered SDFC for flights the next day for $75 and processed SDFC from BWI-DFW to PHL-DFW flight without doing anything to suggest she was circumventing a rule. As always, YMMV.