> The requirements of a UI-driven desktop application don't tend to mesh well with a web-based editor
I took it to mean the parsers for file formats (namely Office). That should be pretty similar no matter what the UI is--you need to be able to read and write the file formats.
With gross oversimplification: office had binary formats (Spolsky has written about clever-clog date handling, now forced to collide with ISO). This binary is/was actually a memory dump of the MFC application, a serialisation on FAT block-based file.
Newer formats are complex, because they are almost an automatic transliteration to XML tags to keep backwards compatibility with the status quo. All this means, that it is highly not trivial to read Office formats without being 100% compatible with MFC. Which is not 100% possible -- even for MS itself ...let alone others (ie. competitors). This becomes apparent, when you try to insert a page, paragraph with copy paste into an existing document within Word: sometimes fitting into the existing OO hierarchy will inevitably fail. This is a long standing wont-fix bug, for good technical reasons.
I took it to mean the parsers for file formats (namely Office). That should be pretty similar no matter what the UI is--you need to be able to read and write the file formats.