It's not uncommon to not want to give information on what you're writing (or what you're working on in general if it involves a story). This also applies to things that are part of bigger works when left without protection of copyright or things like that and when it doesn't feel ready. I figured I'll go into my reason for why I suppose I don't care much anymore, mainly in regards to two major parts to why people are so cautious: one part mainly due to spoilers, and the other being fear of stolen work.

 This is all just opinion and maybe even a matter of perspective, but I think most people probably worry about having what they make stolen more than they should. Art thieves aren't going to get far with anything in any medium and I don't think they are something to worry about in the long run for a number of reasons. Every time I've come across someone who steals music or art it's been pretty easy to tell. If they take the full file and claim it as theirs, it likely won't effect me and it'll only hinder them as a composer or in whatever they do. Nobody gets anywhere that way, at least not in any way that matters, and there will always be someone doing it. I think the only time it matters is when skill level threshold is crossed which logically nullifies any need to worry for me.
 In other words, if you can accurately recreate one of Beethoven's symphonies by ear or make a fake of the Mona Lisa, you already must be pretty skilled. If you're copying something from a lack of inspiration though, you probably aren't very skilled - therefore you won't make something as good as the original. It'll only give highlight to it. Even if art is subjective, it'll never be as good at being art as the original. Especially if you don't fully understand the details and context surrounding it, which only the original artist can fully understand. When I see people copy the work of others it's like watching a monkey do as others are doing. It's usually missing the point of the original or all the other crucial elements surrounding it. If people stealing art understood those things, they wouldn't feel the need to steal it in the first place. I suppose that's the difference between stealing and taking inspiration.
 Of course, I've seen the argument as well that "nothing is original so don't be afraid of being unoriginal or taking inspiration" but I can't stand seeing that thrown around so often. It's an absolute bastardization of the very concept of originality in my opinion and it simplifies things to an exaggerated point that only seems to beg the question of what originality is. We come to this conclusion that we all have the same colors to work with and what matters is how you use and combine those colors, but that's not true. What matters is having an understanding of why those colors work well together, and that's not something other people can steal. Those who rely on that will miss the finer details and make something that looks similar on the surface, but falls flat under scrutiny.

Copyright

 Going into the idea of spoilers, although this applies more so to writing, I think it doesn't really matter if people don't mind knowing things for themselves. Whether spoilers being spoiled matters or not is up for debate, but studies lean towards the latter while in personal experience I've only found it to lead me to wondering how things get to some point or to moments having more tension than they otherwise might have had. This is because we put ourselves into the perspective of the protagonist with an understanding of what they know and don't know. The audience knowing something the protagonist doesn't know doesn't is something that is done all the time and doesn't tend to hurt the story as far as I'm aware. The protagonist of a story knowing something the audience doesn't know without setup or as a solution, however, tends to feel like the writer pulling things out of their ass.
 Things that can be spoiled like everything else require context and setup. If you're relying on something like a plot twist that would be ruined if spoiled, it likely lacks substance. There should be more information behind it that leads the reader to wonder how something can be with moments of epiphany. If you can't have that, then things like the plot twist simply don't hold up.
 Even if you do keep your work hidden until a big release, keeping people from spoiling things afterwards is unavoidable if it meets any success and wanting to do so is a symptom of a bigger issue - the issue of wanting to control the lens of your audience.