What has always made the PR profession so challenging is that PR professional have had to work through the ultimate gatekeepers - the press when a PR professional tries to obtain media coverage on a company, they have to convince a reporter - and usually also an editor - that the coverage is newsworthy. Then, after that hurdles is passed (and it is a large one at that ) the communications professional has hope that the coverage is positive and flattering.
But since the invent of the Internet, everybody that wants to be a journalist can function as a journalist. There are tens of million of blogs on the web, not to mention the hundreds of millions of social media posts that happen each day. Everybody has a voice. Even if that voice is heard by a small group of friends, it has the potential to be passed along and looked up via a Google search by anyone at any time.

That said, the flip side is the potential for misinformation, rumors and even blatant lies to find itself on the Internet. How does one control what is said about them or their company when everybody with a laptop and Internet connection can post whatever they want? Well, they can't.
It is a two-edged sword. While pre-Internet, PR people had to prove the newsworthiness and veracity of a story, which can be difficult, at least there was someone who would tact check before information found itself into the public arena. Yes, there have always been irresponsible and over zealous media, yet there was some manner of control.

The function of the PR professional in today's Internet world is not to spin, cover up of hide information, it is to make sure that what is out there is accurate and truthful. When an individual and corporation finds itself in a crisis, the worst thing that can be done is to try to cover it up, as usually the consequences of a cover up are worse than the original (alleged ) misdeed.