It may because that is the trend as you get older. As a late 20-something my (and my friends) engagement with social media is somewhat reduced. I don't have any content on facebook and don't even have instagram or snapchat. My friends tend to engage less on all of these platforms.

But I'm not sure what I am experiencing is true for other age groups. My boomer generation parents still use facebook heavily as does my early 20s cousin. I suspect there is just a general move away from social media in certain age brackets, but not in others.