Cordon boxes can also be used to cull sections of your map you're not working on, they're not just for compiling. Visgroups can also be used.Cordon boxes are for compiling certain sections of the map. That's not what I am looking for - I am looking to reduce what I see in my 2D view to a certain radius so I can actually see what I am scaling, etc. and not have brushes from many units away also be visible. The 2D view is slow also with my map, so having radius culling made it easier to edit and navigate during editing.
Radius Culling was removed because it's an annoying "feature" of hammer that's toggled through a single key most users don't want to be enabled that leads to annoying leaks if not noticed. It was removed for this specific reason.