Personally, I see little value in them except to make kids think they're on Facebook, which they are not. Without a "dislike" button, they're fundamentally skewed, and people can't be truly honest. I've accumulated >1200 likes on GMTN and many of them are not for technical content, but for snarky or witty comebacks. Can't use them to do much except feel better about myself in a currency with a very small exchange rate to the real world. Just my old fart opinion.
Or do what I do. Assume everybody agrees with me unless they talk back. Then I bite their heads off as a warning to others.