First off, I believe just putting in the time to create any type of content (good or bad) deserves some sort of value. Who best to give that value than the person who did the work on the content. That said, instead of disabling, content creators should be incentivized by the system automatically upon putting something up in Steemit and the diminishing returns would take care of the spam. Actually, since not everyone can put up content consistently, the feature to put all your voting power into one Upvote is really important if you believe what you created, say for this month, really deserves it. Further incentives are then given by the community who finds the content 'valuable'.