No, the reason the F-35 came about over the F-22 is the F-35's cost was suppose to be lower and offered more versatility over a pretty specific role like the F-22 has being air superiority. However it's a bit more complex than that, and we can still and could do before SEAD missions with the aircraft in the inventory that can equip an anti-radiation missile. There's also the JSOW as an option too, but anti-radiation missiles have been used in the SEAD role since Vietnam. The reason the F-35 has stealth is for a higher chance of survival in contested airspace. Threats can range from SAM's like the S-300 to enemy aircraft. To really understand why stealth is important, you need to understand how electronic warfare plays into jamming and how radar works. Stealth coupled with the systems the F-35 has on board for EW should allow it to operate deeper in contested space, and return with a higher chance of survival. Well, if the F-22's at the start of bombing ISIL/ISIS/IS/whatever their name is this week is any indication, stealth is pretty advantageous in going in and leaving pretty much unnoticed until something goes boom. Though it also helps when you have Though you bring up a great point about SEAD missing a site, or not knowing about a site missed in reconnaissance until the radar fires up and begins scanning.