I disagree, think about, go stand at your window and imagine a tank about 20m away or so. Now can you really get a satchel or grenade on it? You may be able to get a grenade to land near the tracks. I'm guessing satchels probably weigh considerable more too, fat chance getting that thing near the tank.
The abstraction effect makes sense to make it impossible from within the safety of a building. Since the tossing of grenades/satchels is essentially the action of the soldiers climbing up on the tank and placing the charge where it can disable or destroy it.
But as a fan of the old CMx1 days of CA from a building existed. How about a middle ground, reduced effectiveness and range when throwing grenades/satchels from a building. But then we'd have people complaining about their pixel truppen wasting satchels/grenades. Damned if you do and damned if you don't.
But the good thing about CMx2 over CMx1 in this regard is that you can split off a AT team from within the squad to make the daring CA of the tank.