Suppose I'm reading a question. It's interesting, I want to help, and I can immediately think of one or two insights that would be useful in constructing or improving a good answer to that question. Unfortunately, for some reason (say, there are system-specific aspects for a system that I personally don't understand well enough) I am utterly incapable of writing a complete answer myself. What am I supposed to do?
The question Should users refrain from answers (or partial answers) in comments? suggests that "put it in comments" isn't the right answer.
I could put it into an answer, but that answer would be fundamentally incomplete. The question Should I be requesting people answer the question independently? seems to indicate that incomplete answers are inherently unacceptable, and so that isn't the right answer either.
Waiting until someone else answers and then commenting on their answer to tell them to put in my thoughts seems awkward at best, and inefficient in a number of ways - possibly rude.
Waiting until someone else answers and then editing it into their answer without discussing it with them seems worse than that.
Having a policy of shrugging, moving on, and hoping someone else comes up with the same idea is unfortunate in its own way. We want to capture useful insights. That's a big part of what Stack is all about.
I don't really care about points one way or the other. Having someone else incorporate my insights into a comprehensive answer while I get no points would be great. I don't even mind putting something out there that might get downvotes. I just don't want to have to drop them on the floor uselessly, and I'd like to be a good citizen in all this. I'm not currently seeing how I'm supposed to do that.