tl:dr - use whatever internet system that has the functions and control of your data that matches your requirements
First, employers are not demanding LinkedIn pages or broadly looking down upon applicants without a facebook...and the idea that they mentioned it in an employment situation, with all the laws in place about fair hiring, *multiple times*...it seems like exaggeration...
However, the question of what kind/how much of your life to share on the internet is definitely a worthy question.
The answer is the understand the function and complexity of the system, the internet in this case. Facebook is one system of many. It has characteristics. One is the default to "sharing".
Instagram is another system...it has less information and simpler controls on "sharing"
**your instagram or twitter can hook into your facebook**
so, a person could use exclusively Instagram, Twitter or even a blog of their own creation, and have it **auto-post** to facebook...thereby having dynamic content on their page without ever going to facebook.com regularly.
the answer is CONTROL
what "social media" internet system should you use?
the one that has the FUNCTIONS you need and gives YOU the CONTROL over your data at a level you are comfortable with