You could go on without doing it. I would like to use signal to signal, but there are literally zero people interested in my environment :-(
Using signal just me would be much better than using whatsapp directly, and would reduce the data collected.
If signal suddenly stopped being mostly a geek desert and people could still talk to all their contacts, don't you think they would be much more willing to move? The more people, the more people interested in migrating, and the less data for meta.