The argument that commercial and proprietary software (CPS) offers greater stability and homogeneity is a very grey area.
As mentioned in Myth #6, additional features in CPS are often the result of the marketing department's requirement to fill bullet points, which will be used later to sell their products.
Of course, this is not just the prerogative of CPS. Open source software (OSS), when competing with CPS, has also been caught in the bad habit of releasing software versions before they are due. Also the sheer size of the CPS market means that there is bound to be more software conflicts and resulting platform instability.
But it is also a question of PR and perception. Whilst we are aware of what’s going on at Redmond, non geeks and the general public often do not care about other platforms because of the lack of coverage.
Because CPS is paid for, it's only right to expect people to nit-pick over details that they would have ignored in OSS. If Myth, a homebrew personal video recorder project, doesn’t work properly on a set configuration, that’s less of a course for complaint because it’s free. In paying several hundred pounds for an equivalent Media Centre, on the other hand, you would expect it to be fully functioning.
As for homogeneity, CPS can often fare worse than OSS. The forthcoming Windows Vista, much like Windows XP before it, will not be compatible with a number of existing software applications.
Patches and service packs introduce a further lot of snags and, on top of this, there are members of the same software family that suffer incompatibilities between themselves – just ask Office 97 users.
Finally, CPS operates in an open environment and, just like OSS, gets constantly probed and harassed by hackers and malware. Stability and homogeneity problems affect both OSS and CPS but the predominance of CPS can make it more of an attractive target for hackers.
You can read about the ten other myths of commercial and proprietary software here.