You are right that using automated tactics need to be toned down, though optimisation can only apply internally, to the site itself.
Let's say you are an SEO company and so am I. Now I feel that your company is costing me work and we are both at about the same level within the google database for similar key phrases.
Now I decide to use some unscrupolous methods and use xrummer to drop 1000's of links onto porn and xrated forums for your site. Also, I use ScrapeBox to drop 1000's of links onto xrated blogs for your site.
Ideally, this method would knock out all my competition
and before you know it, every company online is now waging it's own secrete war against its rivals in this way.
Google would have now created a battleground where black-hat methods will run rife and be used against each other. They know this and I doubt they will allow this to happen.