Why are so many Amnesia custom stories so similar?

[cav500]

I just played the absolute BEST custom story I have played so far, Amnesia Hill - Harold's Story the custom story version. Now, THAT's what I'm talking about! Highly creative, incredibly detailed, cool puzzles, and thoroughly immersive. I couldn't stop playing it once I started. I wish there were more custom stories like Amnesia Hill - Harold's Story. I thought it was better than White Night or any of the other mods/stories I have played so far.