Why? I feel like the internet was started as a place not only to collect and use data but also to vent. It's supposed to be an outlet to say what you want (for me, within moral limits) and not be subject to policing or censorship.
But here we are censoring ourselves for fear of public backlash. We have, in the more recent history of the internet, changed to care what we write about or share because of people who may use that content against you.
How did this come up? This all starts with the fact that I am unemployed. And my friend reminded me that employers / recruiters all do more thorough background checks, including your social media. But the real question is, why do employers want to see what you do outside of work? If that sort of thing mattered, then why don't they state it in their requirements of personality and character in the job posting? And when they see something that is questionable on your social media, shouldn't they have the decency to ask about it before passing you over for a potential job instead of assuming the worst cast scenario and thinking you're scum of the earth based on a photo / blog post / retweet?
Sometimes the background checks go too far. These people act like they've never done anything wrong. And if you truly don't support what your potential candidates are posting and don't want to hire them because of it, then that should be clear. Tell them it's not because of how well they can do the work potentially or how smart you think they are. Tell them it's not because they are well qualified. Tell them they're not getting the job because you didn't like the photo of them drinking a beer or that they voted for Hillary. On the flip side, maybe it's best to take some more time to speak with them to get to know them better before you pass judgement that they are not the right fit, especially if they have all the technical qualifications for the posted job.