The main issues with RU have already been very well covered in this thread. I was on RU from late 2019 to the bitter end. In my first two years there, I saw the very last of those years where RU ran rather smoothly, and I remember there was quite a bit more feedback and activity then. Most of my early stories had UA content because back then, it wasn't an issue at all. There were actual pedophiles there too, but they were a small minority. Most writers simply took advantage of the freedom to create stories that sounded real and vivid, no matter the context.
The issue came from a major societal shift where anyone under 18 suddenly became a "child" and bringing in a 17-year-old character became offensive. This way of thinking really caught traction in the late 2010s. This trend was reflected on the Internet as a whole, with pressure on Web hosts to pay more attention to the content they allow on their platforms. All of a sudden, having UA content in a sex story became a really really bad thing and an extremely sensitive topic.
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So where does that put me as a writer here? I personally feel that the more freedom I have to create, the better. This has to be put into balance with the safety of this site and the vision of this site's administration.
As a writer, I simply have to strike a balance between creativity and living with the rules in place. For some types of stories, I'll be honest, it sucks -- Having bad guys rape three girls and not caring about one of them being 16 or 17 is a great way to establish how ruthless and immoral they are, and there's no real substitute for this. Pure high-school stories are out, and that sucks too, especially for consensual. But for most stories it's not a problem and you can actually have underage characters play an important role as long as they're not sexualized. I'm not gonna lie and pretend it doesn't change anything, because it absolutely does. So I want to strike a good balance and write great, creative stories that are allowable here. I'm very much in agreement with
@Blue about RU's fate.