Why do CAS players so vocally oppose any suggestions

The best part of “Just spawn SPAA bro” people don’t talk about is what are You supposed to do when You already destroy the guy in the air:
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After I killed him, the point where I have been bombed (in Tiger) was taken and my team had problems taking it back. With this SPAA I have little to none chance against most of the tanks, so should I just j out or let enemy kill me and give enemy team more SP? The guy who died in a plane already did his job of allowing his team to cap the point and secure it and he just spawns another tank to help the team when I’m stuck with SPAA that can’t do much on the ground.