Links that can be distributed via any channel and are platform agnostic is great IMHO. You’re then a service on top of any social network (WhatsApp, Slack, SMS, email, whatever).
If you can't communicate your service to others, how do you expect others to use it? The best you can do is make it generic and easy to share however people want.
Supporting SMS and/or email means you can share this service in the most basic means available, and as long as Social Network X supports link sharing, Stuff will support Social Network X.
