Stablecoins are preferred because they maintain a consistent value, usually pegged to the US dollar. This stability is critical for payments, especially when AI agents are making thousands of micro-transactions where price volatility would create risk.

Using assets like USDT or USDC ensures predictable costs and easier accounting. For example, if an agent pays $0.01 for a service, both the buyer and seller know exactly what that value represents—something volatile tokens like Bitcoin can’t guarantee in real time.