FYI, that tactic didn't work against the Soviet T-72s in Afghanistan (except, again, if someone managed to blow off a track). It hasn't worked against M1s in Iraq, and I really, really doubt that it'll work against the Merkava Mk 4s that the Israelis have specifically built for urban warfare and this kind of fighting.
I agree. But blowing the thread or blowing the tank is the same. One less tank in action. 100 kilo HE in an IED on the side of a road takes out the tank. Remember there is a human crew in the steel shell.
In Anti-Tank Warfare never forget the human element.