They did have armies, but the Pantheon had an army of Titans, whom were known to be more powerful then the Elementals Lords. Again, if there were to be an Alliance of Old Gods as there are Alliance of most Titans, I would think the Old Gods would win. If N'Zoth wanted to he could probably corrupt Sargeras' already corrupted mind. Also, yes the Titans killed probably a lot of Old Gods, but who knowd, the Old Gods probably killed a lot of Titans. He wasn't really clear about what he was saying either, so he probably just mistakenly said what he said. Oh, and I did see the video where he said it.