Ken, the F-35 RCS reduction is optimised for one band only and the aircraft does not have a credible jamming capability either.
Tell that to USAF. They insist they do not want nor need EF-18 Growlers because of the F-35s internal jamming capability. I too have my doubts but USAF has a LOT more data than I do. And I personally think the Navy is wise in having a dedicated escort jammer, which the F-35 is not.
If you don't want the bad guys to use their long-range search radars to pinpoint your F-35 package an off-board jamming capability, such as that provided by the Growlers, is rather handy.
Probably true. Yet how many dedicated escort jammers are there in the various air arms on this planet? With the EA-6 retired, the EF-18 seems to be the only Western one. So it would seem that although "handy," such a jammer aircraft is a low priority by every Western air arm except USN. The Russians have old Su-24 Fencer jammer aircraft, but I don't know how well the Russians have been able to update them to keep up with the evolving threats.