I've only done the alias thing for that April Fool's challenge Mare mentioned, but I later added my regular sn as a co-writer so it's listed under both names. I'm not ashamed of anything I write and like having a variety of stories credited to my name.
That said, I get why some people do the alias thing, even within the same fandom. It would be interesting to see if your writing got the same reaction under a different name. Writing should speak for itself, but I think sometimes people's personalities and online behavior either contribute to the popularity of their stories or detract from it. Posting anonymously under an alias no one knows forces people to judge you solely on your writing, not anything else.