Because CAS pilots learn to counter SPAA, whilst SPAA mains learn to complain on the forums.
A skilled heli pilot is very hard to take down with gun SPAA like M247 or Gepard, however a skilled SPAA player (very rare btw) is near impossible to kill with SACLOS ATGMs.
the yorky’s radar range is just barely far enough to track helis from their helipad if you’re at center of map (from spawn it’s too far),
tracerless proxy shots sure are nice, but they simply don’t outway the sacrifices.
Look at my M19A1 stats. Massive difference huh? That’s because planes are rare at M163’s br and mythical at M247’s br, meaning 90% of games result in either 1 plane kill 0 deaths, or 1 death and 1 or 2 tank kills cause I got bored of waiting to fix a problem that doesn’t exist.
M19A1, on the other hand, faces tons of planes, AND it can tank out tanks quite well.