Weight maps are a method of adding a layer of interaction between a figure's armature and the 'skin' mesh that, while adding a layer of complexity (well actually two layers, as the app has to support micropoly subdivision), could also solve problems like the breaking joints issue (of course if the maps are done poorly, the problems could be worse...). The maps are 'drawn' onto the geometry; well, as an example, take the knee. With a weight map, what you would do is bend the knee to its natural limit, then use weightmapping to draw the joint fold as it should look at that point. Save and associate, and if the mapping is done correctly, you get a smoothly folding joint with no mesh breakage and realistic deformation through the arc of the bend.