EDIT: Am I wrong in thinking a Layer with its scale rate set to 0 shouldn't scale? It still scales down when I resize the window?
Scale rate affects the system scaling at runtime, not the canvas/window scaling.
I feel like I had seen a solution to this before in the forums somewhere, I'll try to see if I can find it.
Scaling is still usually superior though, since the dpi of mobile devices can vary quite a lot, and using a fixed resolution/'crop mode' style layout can result in possibly unreadably small or overly huge text. It is usually much better to define a set dimension either horizontal or vertical to fit your content, and then allow the other dimension to get cut off (scale inner) or extend(scale outer) depending on the aspect ratio of your device. Then you set the size and position of your content based on viewportwidth and viewportheight at runtime. Even for apps.
So basically you want something like how a the C3 website displays in different size windows?