Personal Authority is essentially a new badge for the brand of the individual and, as this article points out, it is becoming increasingly important across the board. I would argue that for expert businesses, where a small number of individuals are extremely experienced in a particular area, Personal Authority is more important than any other aspect of branding.
Historically, Content Marketing has been a methodology which was embraced and championed by the marketing department. They commissioned, edited, published, distributed and measured the firm's content. This worked brilliantly in some cases for building a brand (Michelin being a good example).
However, with expert businesses, having a brand that essentially says "We're good at Law / IP / PR / something else" does not help the buyer who has a very specific problem to address. At this point, having an expert who is demonstrably an expert in a specific area (and is recognised as such) will win the firm the client.
Personal authority will become more important. Content marketing has worked well for corporate brands for a while now, but users are gravitating more and more toward personal brands, which are able to provide a more human presence. Personal brands are more trustworthy, more approachable, and have more flexibility than corporate brands—customer reviews and testimonials are rising in importance in a corresponding growth pattern, and as content marketing competition heats up even further, that personal appeal is soon going to be irreplaceable. If you don’t already have the power of personal brands working for your corporate hub, it’s time to upgrade.