Sure, all that stuff about Palpatine making an empire meant to crumble (or at least fall into an inefficient stalemate) has been written into canon, but IRL the AT-AT was designed long before anyone had written any of that backstory. Depends on the angle you look at the lore. I personally try to keep a little bit of looseness when it comes to doing ultra in-depth analysis of tactics, strategy, and practicality of weapons in a setting where the designs originally often came from movie designers who were making interesting and visually communicative designs.