Platforms like HARO do not take the place of having your own contact list for PR. A reporter writing a story uses HARO, or an alternative we like better called Qwoted, to seek out expert sources on topics. When you subscribe as a potential source you get notified of media requests, but you have to watch your inbox and respond fast.
As useful as such PR tools are, they are limited. They put media people in control of the topics the articles are about. The beauty of your own press list is that instead of waiting for media people to contact you, you are in control. You are the one to contact press people and shape the PR about your brand.