In principle... yes.

In practice...
(a) very few people want to volunteer their time to join a social media site and police behaviours. There are not enough hours in the day to counteract all the downvotable content. Also the cost/ benefit doesn't stack up even if you have a large amount of SP. In many ways the Trending page is the low hanging fruit. With delegated SP there are people gaming the rewards in a way more worthy of downvoting, so a certain degree of technical know-how is needed to effectively combat 'abuses'
(b) I'd rather reward as many people as I can that do provide value, which is why I am here afterall. One of the results of doing this is low voting power, which in turn means my downvote has limited impact, that then dilutes the votes I want to give out.
(c) often we're attempting to downvote those who have or have been delegated very large amounts of SP, again limiting downvote impact
(d) people do take downvoting personally, so you end up in petty situations that I personally have no time for.

Again, if there was a "SteemCleaning" Community (rather than just an account) or even better competing Communities that countered voting that the community deems 'abuses', then SP holders could 'outsource' the job of combating abuses (using SP delegation) in a far more efficient way.