Your logic astounds me dude. Regardless of platform, if you're aware you're gonna have a proper chat with someone you'll do it - if i'm texting my girlfriend in a proper "yeah let's talk" mood, i'm inevitably gonna have my phone near enough to me that i'll read and reply straight away.
They're identical ways to communicate - bit of text getting sent at exactly the same speed across the country just with a different name to it ad a different way of charging you for it.