if so it should be flagged or adequately reported

You are right to mention it under curation. Ideally such content creators must be warned before flagging or downvoting. If they don't refrain then it is wise to go ahead with punitive action for the well being of platforms.

understood that the reward system is operated in a convergent linear manner.

As per convergent linear reward system, if the input is low output will be lower. Self upvoted posts are usually of low quality and end up getting low rewards, so at the post payout, output in the form of curation rewards is lower which is neither beneficial for the self up voter nor for the community. Instead users can make use of votes on quality posts to earn better curation rewards.

Vote bots have diminished the effectivene

You have made an excellent point.

Good luck