If it's so good why it hasn't gain adoption? Because main chain long term is not for payments. And you need onchain TX to even set it up so new users can't get on boarded quickly. Those drawbacks overwhelm all the positives unfortunately
Discussion
Because of kyc kliqs!
One doesn’t need onchain tx if the other party online just follow and let the other party follow your nym and be online.
Only if yuh want to pay someone frequently and the other party is offline only then one can send notification tx. Which is 546 sats if using sparrow wallet.