Yes, I am saying that eventually a `page` may have so many locators that it becomes unwieldy and we break it up. 

The other reason I think that passing in a single Region is a bit odd, is that the Region can contain items that have nothing to do with the form.  So a caller can abuse the form filler, using it for everything (not just filling in forms).  However, we could go the route of having a Region specifically to contain the form and nothing else.  That would make sense to me.