Without personas, you may only be guessing what content your audience wants, which means you are more likely to revert to creating content around what you know best (your products and company) instead of around the information your audience is actively seeking.
Furthermore, you personally may have a handle on this information, but does everybody who is creating content in your organization have that same vision of your ideal audience? Documenting your personas, even if it is done in a quick way, is key to keeping everybody focused on the same audience.
http://contentmarketinginstitute.com/2015/04/content-marketing-personas/