[azinman2]

Office is a super giant set of products with a million function, years of versions each their own set of bugs, and decades of files of every kind and subset of features produced by users. I personally have almost never seen another word processing app, for example, 100% successfully load in a non-trivial document from a competitor. It’s just really hard, especially if the features don’t map 1:1, let alone fonts, model of layout, etc. Just the shear number of rendering quirks, subtle differences in math formula implementations, etc would be mind boggling. It’s hard to imagine a more insane (and boring) job.

Kudos to Google for getting such impressive compatibility. Must have been insane amounts of man-hours to achieve. They at least have the ability to crawl the web, download docs and xls, and automate comparison. I’m not sure it’s even feasible otherwise.