Better to focus on personal social media or project's?

When talking about marketing I see a lot of posts about growing your twitter audience and it usually involves building your own personal brand. I feel conflicted about this because it seems indirect and restrictive with respect to the business.

I'm thinking marketing is showing what your product/service is about and how it helps the user solve their problems. If the content is good then is there really a difference if it comes from a personal account vs. a business account?

For personal accounts I worry that if I switch my focus then my account is no longer relevant to the initial audience and may confuse the new one. As "Kyle" I have many interests I'd like to share but as "Business" my only focus is my target audience. But I also get that the connection feels a lot more genuine as you can attach the content to an actual face rather than a logo.

If my content is directed towards a specific group is it more effective to post from a business account dedicated to that group or is it better to post it from your own personal account, provided the content is the same?