I'm not sure if STEEMit has remedied this in the year or so since this post was made, I'd heard something about STEEM allowing canonical links recently, but I only started looking into it now..

And came across this post! So for others who may have found this post looking for the same topic:

Linking outside of STEEM will hurt your readership/earnings for your STEEM blog.. People who follow you on STEEM most likely want to stay within STEEM when browsing content, I think it is way better to just duplicate the post on STEEM..

To avoid plagurism, just put a line in your footer that says "Originally posted to [url], cross-posted to STEEM [date]"

-shrugs-