When you realize that nostr is a distributed ledger with best in class consensus via taproot. Then, you realize #subkeys are essential, because they become sub wallets to your main account. You can pay casually on L1/L2/L3 with subkeys and sub wallets, using on-chain, Liquid, Elements, Fedi Relays or anything else that emerges. You dont want to expose your key every time you pay, just like you have cold storage and hot wallets. Nostr will have the same dynamics where you can instruct a subkey to make write a note, or to make a payment, with minimal risk to your primary identity or wallet.