Captain Seafort wrote:I assume by "didn't exist" you're implicitly referring specifically to the kit available to the Alliance on Hoth rather than generally?
Umm... OK, if that helps. In this facet of the discussion, we're discussing man-pack weapons capable of threatening an AT-AT. Since the rebels were able to equip their troops with all other typical field kit, logistics concerning man-pack equipment doesn't seem to be an issue. Since there were no such things used by the Alliance on Hoth, then, we are led to either: they didn't exist or the Alliance
chose not to use them. It is completely immaterial whether "didn't exist" means in the scope of the Hoth battle, or in general. However, I will say that there appeared nowhere in any form in any of the films a man-pack weapon capable of threatening an AT-AT.
Captain Seafort wrote:True, but airspeeders have an altitude ceiling. This may indicate that their repulsorlifts operate on slightly different principles to those of starfighters. Alternatively the problem might be linked to the main engines, given that whenever we've seen ships operating on repulsorlifts alone they've been sitting ducks.
And if my grandmother had balls, she'd have been my grandfather. Now we're getting into the nebulous vortex of debating the "real" physics of fantastical, magic machinery, and as such the realm of pure conjecture. You certainly could be right; there could be a complete ass-pull of a reason concerning the amount of made-up-ium in Hoth's atmosphere; the Alliance could have considered their X-wings more valuable than their boots.
Captain Seafort wrote:I repeat the point that the Imps made no effort to deploy TIEs in CAS for the walkers.
And it may be a fair point, but we can't assume that inability to deploy is the main or only reason for failure to deploy. We all know from various and sundry examples that strict tactical common sense isn't the prime motivator for the way the Empire does things; the sight of a squadron of AT-AT's advancing alone, inexorably, across the landscape outside the scope of a "proper" military advance in-theater is something which the Empire would relish for its own merits.