The issue with this is that Excel refreshes the active workbook by default after every change. Any quant or someone dealing with huge sheets of formulas learn that you can change this behavior to default to refresh via shift+F9 (I think)

That's for local changes. I think what we're talking about here is a sheet (at one URL) referencing a completely different sheet (at some other URL). The equivalent in Excel, I suppose, would be one .xls file referencing another.