The benefit to having "home on jam" in this case is that it's passive, (no warning to the target aircraft) and generally has a larger detection range than IR. A

The benefit to having "home on jam" in this case is that it's passive, (no warning to the target aircraft) and generally has a larger detection range than IR. AMRAAM has this capability now, which would allow for, in theory, long-range shots without the launching aircraft even having to illuminate. The AMRAAM's radar is short range, so you can use a combination of "home on jam" to guide to a range where the jamming is no longer effective, then go active and potentially make the kill. This is a simplistic example of course; EW being a very complicated subject. But overall, having multiple sensors that you can either correlate or fall back on is the trend in smart weapons right now, and we'll be seeing more of those sorts of combinations.