Dennis - I was not having a go at yourself, but there are NO requirements for airlines to check those details - Your experience may have been awkward from Delta ( I assume, given Atlanta), but they have no right to refuse you for a return flight over the Argentine Tourist Visa Limit - Again, all you have to say, if asked, is that you are travelling around South America, and will be returning from Buenos Airies in due course.
I have routinely bought tickets with return dates well beyond the Visa Limit for entry into countries - including the US. In fact my last arrival into the US was in November, from Europe, I was stamped with a 90 day Visa entry, and my return flight from that plane ticket is November 2010 - I wasn't asked for it, nor was I asked to show that I was flying onto Buenos Airies a few days later to show I was leaving the country.
As for scaremongering, there are some on here who delight on giving out "information" to potential new travellers, regarding a worst case scenario. There are hundreds of people who arrive here everyday who get no hassle from airlines or immigration, and I would suggest that this is far more the case than isolated incidents of over zelaous check in clerks, who should know better. A I say, if even asked, all you have to say is you are travelling around South America, as hundreds are doing as we debate the issue.