I've seen quite some propositions with the word "recommendation" included in the name, and I can only think of one of the closure reasons at StackOverflow:
Questions asking us to recommend or find a book, tool, software library, tutorial or other off-site resource are off-topic for Stack Overflow as they tend to attract opinionated answers and spam. Instead, describe the problem and what has been done so far to solve it.
So... is it really a good idea to create "recommendation" communities?
There is a site for software recommendations that's in public beta and doing fairly well I think (I haven't been to it).
In order for a recommendation to work on the site, is that there has to be a best recommendation. That's how a lot of the sites work, because there's never really just one answer to anything. So as long as the recommendations can be ordered by the best recommendation, then it should be okay.
With that being said, I've also noticed site proposals use the term when they're really wanting to make a site that's asking for discussions, opinions, and anecdotes. Those site proposals fail because they're weak proposals though, and not because they're about recommendations themselves I think.
