It was probably inspired by this:

en.wikipedia.org/wiki/8.8_cm_Flak_18/36/37/41

I have literally stopped researching antitank as a result. Saves resources and in HWW (where you usually have it researched already) you thereby maintain a unit type you can produce very quickly if needed.

AA may be fine against heavy armor, it isn't very good against light armor. At L1, an AT is almost three times better against it, and it only gets worse as tech progresses (4 vs. 15 at L4).

Also, the anti-air gun cannot be hidden. Surprise attacks are valuable.

Ok, fair comments. Surprising light armour is nice. However, a good enemy will scout my units with interceptors and likely also have spied before attacking. Most of the time medium tanks can do the job against light armour but if I were playing with communist doctrine against allied doctrine (mech inf.) or pan asian (light tank) I might use the AT.

Anyhow, you will agree that I have to focus my research - and there is an overlap in capabilities & I definitely need AA. So in general I'll stick to AA rather than AT.