Delegations are not the problem, neither are upvote bots. If neither of these existed, you'd still see the same problems with self-voting of bad posts.
The primary problem is the current blockchain rules combined with the rise of SBD above its intended value has skewed the incentives drastically towards self-voting versus voting for content you actually like. I wrote a post about this some time ago: https://steemit.com/steem/@blocktrades/voting-abuse-and-ineffective-curation-a-proposal-for-blockchain-level-change
RE: How to stop almost all abuse on Steem (Edited)