Yes but, I ain’t joining a random group I found on Internet on a service which has my phone number. Which can be easily traced back to me. Because I don’t know who all the members are then if someone is on the list then that will put me also on the list. If it was something like matrix where even though the group could be unencrypted and open to all. I can use Qubes and whonix to make sure that some stupid idiot doesn’t put me on a watchlist I don’t want.

But if I know all the members and I or someone I trust controls who can join then anonymity isn’t a concern security is and in that scenario yes I’ll definitely be using signal. I already am. But not here.