It's not a matter of needing each other. As long as there's a positive NPV on working together, they'll do it. They each might say, "We benefit X, but there's a risk that costs Y." As long as X is greater than Y, they'll work together. They don't have to, but as long as they're the best partners for a given transaction, why not?

Oh, I agree.

"need" may not have been the be the best word to use there. I didn't mean to imply that either needs the other by the strictest sense of the word. I meant it more in the sense of "I need my morning coffee". I don't really need it, but I'd, you know, really, really like to have it.