The issue isn't about "proving" or anything like that. It's simply that I don't want to have social media. That's my personal choice. Friends are folks who respect their other friends personal choices.
> someone would like to get in contact with you but doesn't necessarily have your phone number
I see this differently: nobody is entitled to my time, or to contact me. If you don't have the means to contact me, that's because I don't want you to contact me. If I want you to be able to reach me, I will make it simple for you. Be that an email, phone number, or what-have-you. That someone random can't reach me on a whim is not a bug, it's a feature. If someone expects me to facilitate that for them, then they have a sense of entitlement to other's time. That's a them problem, not a me problem.
You don't appear to be seeing the important caveat here: if I want you in my life I make that happen. Random people I don't interact with contacting me out of the blue is not something I really want or need. It's entirely possible to be happy with the number of friends and contacts you have. That's not grim in the slightest, it's actually very nice.
> someone would like to get in contact with you but doesn't necessarily have your phone number
I see this differently: nobody is entitled to my time, or to contact me. If you don't have the means to contact me, that's because I don't want you to contact me. If I want you to be able to reach me, I will make it simple for you. Be that an email, phone number, or what-have-you. That someone random can't reach me on a whim is not a bug, it's a feature. If someone expects me to facilitate that for them, then they have a sense of entitlement to other's time. That's a them problem, not a me problem.