Signal is the world’s most widely used truly private messaging app, and our cryptographic technologies provide extra layers of privacy beyond the Signal app itself. Since launching in 2013, the Signal Protocol—our end-to-end encryption technology—has become the de facto standard for private commu...
Removing SMS support makes sense. The potential for a user sending something through SMS that they thought was going over Signal is high. Even for the savvier users who would install Signal in the first place.
It killed adoption, since now it’s just another messaging app. Most of my contacts still use SMS, and will stay on it, so being able to use Signal was a smooth all-in-one experience. Now I have no point in keeping it installed because like 3 of my contacts use it, so it has no use to me, thus killing potential adoption.