Crypto allows for protocols to be monetized in new ways that actually help with fundamnetal problems of existing protocols like SMTP. For example, we can have a bulk-sender fee structure for rate-limiting, so people can pay for more timely delivery. This helps mitigate spam and increases quality of messages sent.
Node operators share in the revenue, so it really is decentralized messaging and economics, in which anyone can participate and earn.
So I imagine this messenger would run into similar problems: if you want to be on the apps stores, they probably can’t use cryptocurrencies, because Apple and Google want their 30%
You've lost 99% of your potential users by drilling down on this. The people that use Matrix and OMEMO today aren't going to give your protocol the time of day; current iMessage, WhatsApp and Telegram users aren't likely to start paying for what they use for free.
Good luck. Just remember that all of your peers on the Blockchain failed to make crypto mainstream, one-and-all.