RE: Throw-Away-Accounts is a problem - I suggest that in order to be allowed to FLAG a post - the account FLAGGING needs to have a MINIMUM of 50 positive posts and more then 100 SP

[cryptos]

This is actually a good suggestion about being able to flag/downvote, a minimum activity on steemit that you need to have... not sure about the numbers as 100 SP might be a bit too much. Though the exact minimum limits can be tweaked...