It is another form of payment. What's to get?

How exactly would you accept crypto payments in your app in a way that avoids the 30% fee?

That feature wouldn't make it through the review process, just like any other form of payment that skips the fee.

Points/karma acquired in-game that can be exchanged off-app for crypto. Since crypto is so easy to exchange with no verification of buyer/seller needed, you can keep moving around how that works to make Apple's task of reviewing your apps more and more complex until you find a way to do it that they overlooked.

Apple’s 30% tax on IAPs is ultimately a convenience fee on impulse buys. Whereas inherent in the process of sneaking Apple-taxable-purchasable under their nose necessarily requires a very inconvenient process: buying crypto from a retail exchange, then moving it off-exchange to a tumbler, then back again to to buy something from the same (or another) retail exchange is far from convenient - and definitely not instant - so it is not in any appreciable way to circumvent Apple’s IAP tax, because it simply comes down to the fact you can’t make impulse-buys through that system - never mind the txn/gas fees in cryptocurrencies make it very wasteful for microtransactions, or really any transaction below tens-of-dollars.

I’d agree with you provided Bitcoin’s Lightning network worked the way we hoped it would back in the early-2010s, but it doesn’t. Otherwise, your argument reads like is saying Apple should tax every PayPal transaction made through PayPal’s iOS app.