Sorry, but a restaurant still has no business checking my social media.
They want to see if you're a dick or annoying or a whiner or anything else which might interfere with their restaurant ambiance.
Would you want someone who posts how often they get drunk at restaurants at a place which charges $500/meal?
But as the article also relates, they want to tailor your experience with them. If they see you've announced you're on a diet, they won't suggest the high fat stuff but instead something they think might be more appropriate based on your postings. Or maybe you mentioned how you would like to try XYZ, but never had the chance. Guess who will give you that chance.
For places like this, it's all about personal service and making sure your stay is comfortable.