Companies should not just hire anyone who can do the job. To create good morale around the office, if you have a pool of qualified candidates than it is important to know who would best fit in among the other employees. How a person chooses to present themself to the world through their social media page can say a lot about what they will bring to the company not just as an employee, but as a person.
Employers have no right to look into a candidate's social profile when it comes down to hiring someone or not. Doing so violates a persons privacy and allows the company to make hiring decisions based on it, which is not fair. Employers need to evaluate the prospective employee based on his/her interview and background.