I'm not sure if the creators of Steemit are able to ban users or not but I will assume they can't otherwise the word "decentralization" won't mean much ?
I'm watching few posts at the moment in order to find any BOTS , till now I found one :
https://steemit.com/@nastrom/posts
I want to compile a list that way users don't mute them/don't up vote them or whatever.