Plagiarism is a grey area on Steemit we all have to learn our knowledge from somewhere to begin with. 'When a baby is born it knows nothing' I would consider it cheating if you had copied another users post but getting information through study of other independent web sites if you ask me I think it's harsh.
If I teach somebody something it's knowledge that I had to learn before I could possibly teach it so I don't find it logical that I own that knowledge my student owns that knowledge or the person who taught me owns that knowledge.
I can own a certificate to say that I am competent to teach certain things but I cant own a certificate to say the knowledge is exclusively mine.