Becuase they have a vested interest in...well, playercards.
I can't seem to understand why there are people still bring up the Lt/Cpt/Major tech compare to OKW one or side-tech upgrade. You people are just lengthening the discussion for no particular reasons anymore. What's the point of that!?
As for flak tier, give it same AA radius as Bofors? No one's complaining about that thing, and that thing comes earlier, cost less, and works much faster, and you can build more than one. Hell I'd take a Bofors over T4 any day if it wasn't for the fact that you HAVE to get T4 if you want to win the match under 2 hours.
I'd also think that part of the problem is that it's not affected (or as affected) by smoke, I've seen times where it continues to fire even when smoke seems to obstructed other units' vision. This might be due to the structure's large size- other structures like bunkers can be blocked by smoke, either from wrecks or smoke grenades.
Of course if not, then that does raise the question of why not just smoke the bugger and drive around?
As far as I'm concerned, the exact opposite (or identical) group of people are those that constantly say UKF emplacements are cancer: they know the word "free" will convince people to make the change.