Agreed 100%. If the swap wasn't there, the OOM killer would just do whatever it would do when the swap ran out, and it isn't busy thrashing for dozens of minutes up to that point.

That said, sometimes it is unfeasible to have as much RAM as you need, due to cost or architecture, and you have to use swap. But, IMO, it makes more sense to add swap files on the fly than have your system come to a crawl because of a runaway process that you're going to want to kill anyway.