There are a great many friends where Life Happens™ and although I genuinely care about them, I haven't contacted them in months / years (and vice versa) because I'm not generally the type to initiate small-talk. That doesn't mean I don't enjoy catching up with friends and going over the little things in our lives, it's just not something I naturally do. Having an app that helps you keep in touch with the people you care about (if you don't care why would you bother to set up an app) seems helpful.
And I think stating that this is not introversion but more like psychopathy is a bit beyond the pale. It can be hard for introverts to kickstart conversations with people they haven't talked to in a while for various reasons, none of which are "because they're a sociopath". They might feel like they're intruding or they might have confidence issues which cause them to feel that messaging people out of the blue will make them seem weird, even if neither of those things are actually true from the other person's perspective.