There is nothing that can be done about the 15 SP Accounts that do nothing other than down vote. They have no content to down vote, steemcleaners has nothing they can do about it, the only one that can do something about it is @steem.

For accounts created solely for the purpose of down voting other accounts there is nothing that can be done about them either. If an account goes mute and then 8 days later decide to do nothing but down vote there is little that can be done about it.

The anti-abuse accounts are able to help with the accounts that are activity posting or commenting, if there is no post, no comment no response to stop the actions they are doing, then there is little that can be done.

The removal of the delegated SP from this type of account is the only thing that will slow the actions down. If you believe these accounts are harmless, just look at some of the comments that have been left on the one and only post those accounts have. They do have an effect on people, especially on the new users to steem block chain. Trust me it is not a good effect on the new users either, all they know is some asshole down voted them and there is no one to turn to for help, that is the reality of those 15 SP accounts actions on people.

Those new users do not have much more SP than those down voting 15 SP accounts. Any one that believes they cause no harm are just not looking at the harm that has been done because they may get cold feet about Steem Token. Retention is a problem on the Steem Block Chain, there has been ample post about retention and keeping people on the Steem Block Chain,