Sure, you can still e-mail, call, sms or heck, even visit your friends and family IRL. But not having a social media account sure makes it more inconvenient. All your friends use these networks.
In a couple of years not having a social media account will be seen as equivalent to not having a bank account, or a passport, or a phone number. Sure, it's possible to live like that. But it sure is inconvenient.
Aside from that, as others have mentioned in this thread, even if you don't have an account Facebook, Google, LinkedIn, etc. have your data already. You can be sure one of your friends has uploaded their contacts to WhatsApp, including your phone number and mail address. Facebook has detected your face in a photograph your cousin uploaded. Google has all of your self-hosted mails because all of your friends use Gmail.
If you don't want your personal information to be shared, you need to live like a hermit.
