the AEC is what the brits should be using against an early light vehicle or tank.
The british doesn't have any tank snare and their PIAT have difficulty hitting moving vehicles, so logically the AEC is there to cover up the particular weakness.
True, but a 6pounder is probably better against most light vehicles (excluding flamer 251 and luchs). This is the problem of the AEC, it's kinda like Penals in the way that its role can be performed by another unit that's better at it.
Also for people who don't know what the AEC's cost is:
100 (tech) + 340 = 440 MP.
15 (tech) + 50 = 65 FU
OKW Puma costs 320 MP and 70 FU (pretty sure the ost one has the same cost)
And Alex logic can't work here, the tech only unlocks the AEC, so it absolutely is included in the cost.