I wouldn't consider a candidate solely on social media, but it might introduce me to someone's work which might then encourage me to look at their portfolio and maybe have some casual conversations. I consider it marketing. As far as hires go, I've had 4 industrial design hires hires over the years that I first had conversations with here on the core77 boards. A fifth is someone who I first met at a car's and coffee event. Then ended up following him on instagram. We got together for lunch a few times, and when I started my own studio he was the first contractor I brought in. Then ended up bringing in a second through his recommendation.
Don't think of social media as a one stop, single point decider or influencer. Decisions like this are typically made on a constellation of data points. Recommendations, past work, initial impression of personality, social media footprint, cost, availability, capabilities, are all factors. I'd be suspicious of anyone who saw an instagram photo and then wanted to spend six figures with my studio... I guess unless it was someone like Elon Musk who has his own social footprint.
As far as showing work, I try to show a lot of work that is production. When I was doing the 365 sketches thing (finally finished all the captions yesterday for the book BTW... now it just needs to go through my proof reader so I don't have mistakes like lab pointed out
) I was posting a lot of new content, but that content was for the purpose of this book which is another marketing activity. Now when I post a sketch it tends to be because I had a little time or I just needed to get a sketch out of my head and I wanted to share it. I think it is a mindset. It isn't transactional, it is about building a clearer image of who you are in the digital world now that clients can be anywhere. Some clients like to pay to have us come out and do onsite work/research/workshops, others are happy to never meet in person. For that second group, your digital footprint might be a big part of the picture of who you are in those first few interactions when you are hammering out terms, deliverables, costs.