Getting Back to Keeping On

I am becoming sadly cynical about people who don't follow through with their undertakings to "get back to others." Sure, I've missed or forgotten a few deadlines, but despite the constant to and fro via Twitter and Facebook and other social media, it shocks me that people who say they'll get back on a subject, very often don't. It seems to me that it's trending. Is it that there is just too much noise out there for people to remember what they said they'd do? Or is it that today's tweets are more important than what we said we'd do yesterday? I still prefer voice-to-voice (if not actual face-face) communications. I sense that with the dwindling use of phones as phones the "etiquette of replying" is dying. Any comments?