That's a fantasy that SimpleX will ever catch on over Signal. You have to look at in the sense of path of least resistance for that mass market, not one individual person to another individual person. Keep in mind why it's too difficult to sign up for a Mastodon account so it's easier to stay on Twitter. People promote the benefits of Mastodon but nobody has ever built any success in the mass market or built a name for themself on Mastodon over using Facebook and Twitter. Name a company that people know in other countries and only uses fediverse exclusively. It's the lowest number you can think of. As long as people have someone's Twitter handle, everybody can find them. That's why Signal is the best option, because people only have to post their username or give out their phone number, and everybody can be found on Signal.
For example, if you and I have a mutual contact, you could tell them to message me on Signal and you give them my info so they can talk with me there. If a company starts using Signal and posts the company's number saying they are on Signal similar to how a lot of companies outside of North America use Whatsapp with the company number, the company can also use Signal as another contact option. That's why SimpleX will never grow beyond people who pay attention to protecting persona privacy.
Look at PGP, it's 30 years old, how many times has a person asked you for your public key?
Only if you do not register your phone number with any service like Signal, bank does not require 2FA before you can access your account, and you never need any company to send you a message.