In days of yore, you usually made new friends by meeting in real life. Staying in contact could be a bit harder. If they lived in same country, you could use the phone, even if long distance could be a bit costly. If they lived in other countries, you had to resort to (snail) mail, unless you had access to free phone, e.g. from your employer. I am talking about the time when it was still very expensive to phone internationally. In the 1990s, email became quite common, so it became much easier to stay in contact. But there was still a risk of the other person changing email address and losing contact that way. Furthermore, anything that require some effort to uphold contact, makes the likelihood of drifting off from the relation bigger. Especially FB has changed that a lot. There it is quite easy to stay in contact or dig up old acquaintances. Correspondingly, it is harder to hide from those old “friends” you really want to avoid 
These days we make new friends across the globe. We meet in online communties, via blogs, or even sites like FB. Many of them we never get to meet in meatspace, but we still count them as friends, more than “acquaintances” or “contacts”. I have very few friends and acquaintances made online that I later have met IRL. One reason is that I am not very mobile, due to my health. But that is just a part explanation, I think many make good online friends (not just FB “friends”) they never have the opportunity to meet.
Today I learnt, via FB no less, that such an old online friend had passed away. He was not one of my very closest friends but we have known each other since 2007, and while he was no youngster, it was sudden and a shock. We are touched and moved by persons we get to know online. We have good laughs, get insights, advice, help, well-meant critique, hugs and maybe even adventures. Even if we never meet them in the physical world.
R.I.P. Rob. You will be missed.