admins know better
Why should Apache compete with a web server placed on the end user's desktop?
Setting up an own litte (pirate) website is surely not most common use for IIS nor Apache.
All admins dealing with webhosting i know LOVE Apache and HATE IIS.
Not because IIS is from MS but because it's hard work to configure IIS and Apache is not
(having magnitudes of several thousand customers).
Yes, you have several tools/facilities in IIS for this purpose but this make it even
more complex (IMHO).
As for reliability: even Frontpage server extensions run better with Apache...