I know the Imperial Walkers line. My point was that terrorist groups work in cells, so while they have knowledge of walkers they might not know how to defeat them. Of course, the AT might be the ACTs superior and they've never faced it. Maybe the laser turrets work on the ACT? I mean, the Rebels had time to construct an ion cannon.
I just don't want the Rebels blowing up ACTs so easily in Rogue One otherwise it appears our band of Rebels really is pathetic when it comes to Hoth.
But we're just debating the plot holes of a sci-fi movie now.