If the F-35Bs advanced systems and capabilities are not needed in Syria, then why did the USAF insist that the F-22A was necessary to defeat Syrian air defenses during the initial airstrikes in that campaign?
The thinking was that if air power was used against Syrian forces in direct support of rebel forces, that the Syrians would use their air defenses against such aircraft. That never happened. Instead, air power has been used to target ISIL/ISIS forces, which effectively
supports Syrian forces rather than opposes them. So the Syrians have not used their air defenses against those aircraft. If things changed and US and/or NATO forces were to directly target Syrian forces in direct support of rebel forces, that would likely require F-22/F-35.