I don't think it's quite as black and white. LinkedIn is just one channel, but I imagine you're going to have a hard time finding a workplace where social credit isn't a big part of internal politics. Whether that's being charming, great at your job or using SoMe, it's all about people.
I doubt any company primarily uses LinkedIn for promotions, but it does help your career if you are known for something positive by the people who run the company you work for.