This sounds like a reflexive "I hate blockchain and cryptocurrency" reaction but I'll give a reply regardless.

You can't do transactions with just a database. You'd have to add a payment processor. Now things are getting wildly complex.

x402 is designed with agentic AIs in mind. AIs make mistakes. Having an immutable record that can't be tampered with is a nice layer of security.

And while I haven't worked with it personally, I understand x402 to be extremely straight forward for devs to implement.