Alien.top’s raison-d’etre is to create bots and repost things from Reddit.
The instance makes a bot with the same username as the poster from reddit, then makes a bot with the same username as all the commenters, and re-posts each comment.
Every alien.top user in this thread is a bot.
https://lemmy.ca/post/10599153?scrollToComments=true
I did a quick check, and it looks like 138 of the comments are bots.
I had the same thought process as you did!
When I thought it was just people cloning their own accounts, I didn’t see why anyone was against it.
Once I saw that the bots weren’t made from a request duplicate made the the original user, and that they almost exclusively post outside of Alien.top, I was very against their existence.