Replying to conversation about fanfiction (days old but it's an interesting topic): It's better to just not read fanfiction of your stuff because, like it was already said, it opens up a ton of copyright and legal minefields. "Oh look they read it and now they're using it, HOW DARE THEY WHERE'S MY MONEY AND CREDIT?!" Spending money and time on crediting people for their ideas can be a good alternative, but you're ultimately having to tiptoe and pussyfoot around them as you're opening yourself up to criticism as it's not a good look for an original work to suddenly piggyback on what some person wrote (regardless of quality). That's assuming that the fanfiction writer is someone who's nice and isn't looking out to sink them (pun not intended). If they're like the latter then HELLO needless lawsuits and out of court settlements. Unnecessary dangers, risks, stress, sleepless nights, etc. for not much return.
It's why writers, copyright holders, and such don't entertain fanfiction as it has more potential to bite them in the ass. When you have odds that are astronomically weighed against you for doing a thing, you're not going to do the thing (unless you're a terribly written shounen anime protagonist). Basically, yes I understand why this policy (which is basically universal) is still practiced; it's not worth the headaches. And I support the practice honestly. We're not talking about terrible microtransaction models, or DRM, pre order/hype culture, or any other toxic business practice; we're talking about a practice that seeks to protect their baby without infringing on another's baby. Plus, as an addendum being a "writer" myself, it's really hard to convey how much work goes into creating original work (hey don't raise your eyebrow at me). The idea of taking somebody's fanfiction and using it "officially" (ie like some users have suggested), regardless of the astronomically bad odds already mentioned, it would still be a massive headache to rewrite/reconceptualize/redo EVERYTHING so it fits. I have fits when I have to rework stuff because of minuscule changes I've made, having to take a fanfiction and making it work effortlessly so it looks cohesive? WOOF, no thanks. It's too dangerous and too intensive to bother. And to make something clear. Writers/copyright holders/etc. do enjoy interacting with their fanbase, as a rule (always an exception or three). They just won't listen to ideas, fanfiction, and all of that because of the aforementioned mess. This is an interesting write up that deals with the topic.
OH, and second addendum. Reading fanfiction "poisons" a writer. You can't take back what you read, you take it with you. Yeah yeah I already covered the legal ramifications, but not the emotional. Your work will be, invariably, affected by that new POV of your stuff. Meaning that if it was bad then you're like "ech, gross" but if it was good then you're like "man why didn't I think of that" and then the rabbit hole goes deeper and deeper. "Should I use it and change it? Should I not? What if it shows up tangentially? How much deniability do I have if i'm accused of ripping off this or other fanfics?" etc etc etc. The best policy, like in medicine, is to prevent it. Seeing what someone else does with your stuff doesn't really have many (if any) pros and a huge list of cons. I'd be flattered if people wrote fanfic about my stuff, even more if it was fanfic that was well received, but I would never read it.