> With messaging apps you can use both Whatsapp and Signal
You can have both Whatsapp and Signal installed, but everyone in a conversation needs to have the same app. So why not both doesn't apply as neatly as you assert.
Sure, but that assumes you only have one group. I'm in only 2 really small groups, both on Signal, but I keep Whatsapp because there are a few people I can only talk to there.
It's also a backup mechanism in case Signal fails (like it did when the exodus happened)
That's true, but the people I talk to on Whatsapp are not (usually) in the same country as me, and cross-border SMS tends to not be included in a basic package. Especially now that UK has left the EU, that's definitely not going to be cheap. Add to this that cost increases with message length in SMS - over the internet it's basically flat if you have wifi or data (up to a point at least... :D )
You can have both of them installed at the same time, so anyone refusing to join a Signal conversation is just going out of their way to be a pain to deal with.
Eh, I already have enough messaging apps myself (4 right now), so adding more at this point is a hurdle I'd like to avoid. I can imagine others having similar feelings.
You can have both Whatsapp and Signal installed, but everyone in a conversation needs to have the same app. So why not both doesn't apply as neatly as you assert.