There's one thing I don't think I've seen mentioned each time the feedback discussion surfaces. (And didn't we just have it within the last six months? I thought the cycle was supposed to be annual.)
As well as all the "feedback is payment for writing" or "feedback is a thank-you for writing" or "feedback is a precious and undeserved gift", for an author, feedback is kind of like market research. It's like being a retailer and looking at your sales figures to see what's moved the best.
I don't imagine that most of us cold-bloodedly look at our stories and tabulate the feedback and then make our to-be-written lists based on that. But still, if you have more things on your to-be-written list than you can ever write and all other things are equal, you're more likely to consider the type of story you think will get a good response. After all, why share a story that most people don't want to read?
If you spend three months writing a story and it gets X feedback and you spend an hour writing a drabble and it gets X feedback or even X/2 feedback, you might think twice about spending three months on your next story. Substitute pairings or fandoms or subject matter for length there and it still holds.
So, when you send feedback, you're not just saying "I liked that story", you're saying "write more stories like that one".
That is my theory, it is mine, and belongs to me and I own it, and what it is too.