Same could really be said about any light tank... Mines, hand AT, snare, maybe camod t0 AT gun... If it didnt have a counter it wouldnt be fair... Game is all about counterplay back and forth (well, that or attack move)
The thing is that Stuarts, AECs and T70 are shock tanks that help you to get a bigger advantage in the mid game. Of course the Luchs also has a big shock factor as it rips inf apart in seconds, but in this case it acts like a single counter to a current Meta strategy. Lose your Luchs and you lost the game. Lose your Stuart/AEC/T70 and you lost a lot of fuel but by no means the whole game as they are not necessarily needed to counter something.
And still all Light Vehicles can be countered fairly well by all factions IMO. Only Ostheer, which is not the topic of this thread, has a hard time.
But
Sovs: Even with T1 they have AT Penals, can build Cons with AT nades, T70, Mines
USF: Bazookas, M5, M20 AT Mines (hahahahhaa)
UKF: AT gun, Sniper, PIATs, Mines
OKW: Raketenwerfer, Fausts, AT Sturms, Mines