It's literally impossible to make a full-time living on Steem right now.
I'm one of the most generously rewarded people on here, and will maybe earn the equivalent of $200-300 USD per month. Impossible to survive on.
And even if I did make the leap to post exclusively full-time on Steem, there's absolutely nothing preventing one or two whales from downvoting my content like they have been over the past week, on three occasions.
And this is the problem with down voting for "overrewarding" too. It makes it impossible for people to earn enough on Steem to post exclusively.
If I can earn $60 on a YouTube video, why would I post exclusively on Steem when (especially after downvotes) I might only make $5 on a video? Rational people won't do that.
So you're preventing people from going full time on Steem. If you want a platform full of hobbyists, that's fine. Or only people who are so rich that they don't need financial compensation, that's fine too.
But Steem won't attract professional content creators with this overrewarding downvoting nonsense.