The only time really that the origin - as a discrete point in space - means anything is for grounding your first sketch or your first part in an assembly.* In general, everything else will be dimensioned relative to another feature.
Stop thinking AutoCAD. This isn't AutoCAD, and if you try and work with it the same way that you worked in AutoCAD you're just going to be frustrated instead of productive.
*Yes, I know there are exceptions.