The biggest complaint I have is that all too often whatever personal information we thought we had on the web is and was no longer personal.
I agree with @Lorna when it comes to employers doing background checks they now request/require your social media user names, some ask for passwords if the pages are set to private when filling out job applications. If you have a chronic illness that may require you to take multiple days off work, and are in the market to find a new job, do you pose some sort of risk for being able to do your job? This sort of prejudice can also show in family's who have multiple kids that are in multiple activities or in families with kids who have some sort of malady. If you have a child who has special needs your time at work could be jeopardized if medical / special care is needed at home.
The old adage kicks in: Perception is reality. Even if you never missed a day of work or an occasional day and have had an illness for a while, once the cat is out of the bag, now everything you do could be scrutinized. Think about the young workers just out of college today. Many of them have pictures of them partying on Fri/Sat weeks or months ago and yet miss work one Monday and suddenly they are labeled or called out. Or what about a husband and wife on the rocks. Does that suddenly discredit any decision that they have made while their family is in turmoil, because people who are under duress can make rash decisions.
Then on the other hand, how soon will it be that someone will talk about a chronic illness and suddenly get targeted for research drugs, advertising etc.? Or asked to participate in other activities regarding their illness. While almost all are looking for a sympathetic ear, most individuals don't understand how far the reach and lack of privacy they have when they post things in social media.
It's not fair by any stretch of the imagination that in this day and age we could be discriminated against because we have an illness, but making it easier to track on social media is just begging for issues.