Originally Posted by
cfischer
It is obviously untrue. They can do it. No technical limitation. That said, they are not supposed to do it and agents can get in trouble for it. It still sometimes happens, for me most often on high value corporate fares.
They absolutely can do it, both agents (none has mentioned anything in the past couple years about "not supposed to" though that was the line in the not-too-distant past) and automatically (well, some of those "automatics" may be agents working magic behind the scenes) -- in the latter case the app will usually do a "Because you may (miss your connection/otherwise be screwed) we've [protected, I can't remember the customer-friendly term they use] you on a later flight but you are still confirmed on your original flight." pop up
I think new (only trained on Aero/Jet, not on SHARES) agents are less inclined/willing/knowledgeable about how to, and res agents tend to be more hesitant about doing anything to a (potentially) IRROPed itinerary than airport agents, IME. Res will typically default to straight rebooking on UA only unless you get a particularly seasoned agent and politely insist, but I also have strong reason to believe status is a significant factor as well. (None of my fares are corporate but nearly all are on the pricier side)