we (i am a student) are required to post every source we use when writing assignments. "wikipedia" is not seen as a valid source, we are allowed to use it to gain information, but if we want to incorporate any of this information IN the actual assignment, we are asked to provide the source BEHIND the wiki (references part of wikipedia), but mostly we are discouraged to use wiki as source, we are usually provided with better alternatives.
so there is that, and i agree with that sentiment for a large part.
i do use wiki heavily for my own leisure, as in "start reading one article, see another through a link, realise its 2 hours later" and if you ask me thats the main point of wiki.
so basically i am discouraged from using wiki for official purposes.