Rightly said. Quality of posts collectively in a platform like Steemit is what determines the value of the platform as a whole.
We could be having some moderators (like how we had in forums back then) who filter out the spammy posts of zero value before they're even posted but on a large scale, it does become a little difficult. We could work on achieving this by mutual understanding between the members to work on increasing the value of platform as a whole.