The user interfaces on most wikis I've seen (including Wikipedia) are not really usable by casual non-technical users. Thus, wikis, if used in businesses, tend to be in places like software development groups, and those groups can easily set up their own wiki if they want one - there are dozens of free, open source wikis to choose from. (I set one up on my machine at work.)
At my company, the non-developers use software like Microsoft SharePoint rather than wikis.
Still, there are already a whole bunch of hosted wiki services. You can find a list on Wikipedia:
https://en.wikipedia.org/wiki/Comparison_of_wiki_hosting_ser...
So you'd be competing with these established companies.
