the reasons, at least from Microsofts POV, are pretty well detailed and mostly involved backward compatibility and fidelity concerns. For example, and I forget

the reasons, at least from Microsofts POV, are pretty well detailed and mostly involved backward compatibility and fidelity concerns. For example, and I forget the exact numbers, at the time the OOXML spec had in the region of 300 pages of documentation around functions and formulae in spreadsheets, and the ODF spec had 6. Fleshing out the ODF spec to the point it would be suitable is a headache that I imagine MS didn't want.