Although they word it poorly, I think the point is that those numbers should be compared to similar software issues experienced on Windows platforms, in which case the benefit of switching back is a lot slimmer. As noted a bit later:
> Incidentally, 15% of users acknowledged severe issues related to MS Office.
You have a point in that it's very easy to interpret these statistics in totally contradictory ways, but without further details we are just speculating.
> Incidentally, 15% of users acknowledged severe issues related to MS Office.