I guess I am just saying this could be another example of not completely being able to forecast how this would work in reality. You say it will be likely downvoted, but do you currently know how many posts get downvoted or why?
Other than pure flag wars between people and the current whale experiment, I would say most of the flags I see come from people like steemcleaners in an attempt to fight abuse. I'm not sure self voting would really fall into the abuse category and your average user isn't going to check the authors voting history and the % power of those votes when they read a random post.
How will the average user know that random author John Smith only upvotes his own posts at the max % allowed? Even if you did a little digging on every author of every post you read, how much upvoting yourself is too much? Using 90% of your voting power on yourself? 80, 70, 60.. where do you draw a line that says this cant stand and I should downvote it?
I agree. People are not going to waste their voting power to downvote self-voters, it's not going to happen unless they have real incentives to do so.
Like you said there is no way to determine if the self-voters deserve a downvote, this is going to create a very toxic environnement if people start to downvote left , right and center.