User blog comment:D.Dragon123/Why Haoshoku haki is useless./@comment-3119203-20130115000608

In combat, Haoshoku is a time-saver. It allows you to take out huge numbers of random subordinates so you don't have to waste time and energy fighting them yourself (makes me wonder why Whitebeard didn't use it at the beginning of the war.....). Against strong opponents, it's essentially useless, as you can't use your mind to knock out someone of a Shichibukai or Vice Admiral's caliber.

What it really is is a strength indicator. The Haoshoku is a mark of those who are apparently "destined to lead", as shown by its presence among very powerful and influential figures. If someone has Haoshoku haki, it means that they have very powerful life force and incredible tenacity....hence the reason Sengoku and everyone was "scared" of it. Not to mention the havoc it could wreck upon Marines if properly controlled. Just look at Luffy, he took down 50,000 people with a glance. Imagine that power harnessed at Marineford. Sure, the numbers would be lower, but it would still be powerful.