This forum isn't going to be the best place to get solid pros to having a partnership, you would need to explore a few more places (like forums with less intj's), to get a list of reasons in favor of having a partner in business. For reasons not to have a partner, as you can see, this forum is a great resource.
It looks like a safe bet to say that affiliate marketing attracts a majority of lone wolves.
Also consider, people are more likely to complain about a bad experience than they are to praise a good one. You don't see nearly as many happily married men talking about how great their marraige is (and when they do, they are usually accused of being whipped), but you can't go a day or two without hearing about the woes of someone getting divorced or how annoying they think their Wife is (oddly more acceptable to bitch about the only person who tolerates your shit, than to appreciate them publicly).
