Some anecdotes I heard in the past was that Microsoft lost some of the source to it, either that or the source is such a huge mess it would need a virtual rewri

Some anecdotes I heard in the past was that Microsoft lost some of the source to it, either that or the source is such a huge mess it would need a virtual rewrite to get it to be portable. Though probably the most likely one is that it was too much work to adapt the db engine to something other than the MS filesystems, as the program has existed since the early days, and the code is probably deeply rooted in MSDOS.