I don't make the choice of how individuals in my social circle uses to communicate. Giving up being in contact with some of my friends/acquaintances is too bad a trade-off.
Your friends don't have WhatsApp or Telegram?
Unfortunately not really an option in a lot of business. There's a ton of services where Instagram is both your portfolio and an important first point of contact.
I made a similar app, it’s called “Only DMs” free on the app store :)