The Bank for International Settlements' Hyun Song Shin( believes that stablecoins' reliance on decentralized blockchains inherently causes liquidity fragmentation, as validators need to earn rewards through congestion fees. This results in multiple non-fungible versions of the same stablecoin across different blockchains, thereby weakening the network effects necessary for a universal payment tool. His working paper points out that blockchain congestion is a necessary feature, not a flaw, for maintaining validator incentives, which prevents stablecoins from truly achieving monetary unification.