That’s a major boost for those that might not particularly care about encryption to look for specific messaging apps, while still helping by building out the network slowly over time.
This became much more of a problem for me after they rolled out their shitcoin; suddenly my techie friends were just not responding to messages, and Signal as my main SMS app was not falling back to SMS for these folks.
The user cannot just log out of Signal and have the app on other people's devices automatically fall back on SMS the way it works with iMessage?
Logging out might not even be enough, depending on the logic on Signal’s side. Do they use active devices, or just that an account exists?
I’ve only done the switch from iOS to Android once and I remember it was a pain for a few days until everything realized I didn’t have iMessage anymore.
For two weeks, messages will be shown as sent but not delivered, and after two weeks Signal will not let you send messages to that number until it reconnects to the Signal servers.
For comparison, Apple automatically sends all SMS messages via iMessage opportunistically, and if the user then switches to another phone, all SMS messages from iOS users will be silently discarded in perpetuity. This is a big problem because the recipient has no idea that they're missing messages, and also if they no longer have access to an iPhone, there's no way for them to deregister their phone number from iMessage.
https://selfsolve.apple.com/deregister-imessage/
They will also deregister you automatically after some period of time. What you described is the situation several years ago, but it's much better now.
In that case, Signal's current behavior would be comparable to Apple's, if Apple also deregisters you after a period of inactivity.
I'm willing to bet that this decision is just jumping the gun by a month or two since usernames are around the corner (code exists, just not enabled. Can be used if built from source).
Though I haven't had a hard time converting (Android) users by using another app. Especially people that already use WA. The "other app" just comes off as normal. Apple is a different ball game because the walled garden, but that's also the weakness because you can't send photos/videos in group chats with mixed devices (but Signal can).
It also puts a spot-light on the "your phone number is your username" policy. This made perfect sense when you are using Signal for opportunistic encryption of texting. It is much less justifiable when using it as a Silo'd app. I really hope they change that and give people who were waiting for that change time to join before killing SMS support.