I sometimes think the most important part of a blockchain is not what it promises, but what it silently rewards. You can say “fast” and “cheap” all day, but incentives write the real story. If Plasma is built for stablecoin settlement, then the uncomfortable question is simple: when stablecoins move at scale, who decides the order, and who benefits?
MEV sounds like a niche term, but the human version is familiar. If two people want outcomes that can’t both happen, the one who controls ordering can choose a winner. In trading, ordering becomes profit. In payments, ordering becomes priority: who gets processed first, who gets delayed, and who suffers when prices move between “submit” and “confirm.” That’s why fee design and transaction ordering aren’t “details.” They decide what kind of system you actually built.
Plasma’s pitch includes sub-second finality and EVM compatibility. Speed can change MEV, but it doesn’t remove it. Faster confirmation shrinks the time window for everyone except the actors closest to the ordering engine. The market doesn’t disappear; it becomes more latency-sensitive.
So the first thing I look for is: who controls ordering in practice? In many BFT-style systems there is a leader for each round. That leader sees transactions first and decides what comes first. If stablecoin settlement is the main lane, the leader’s choices aren’t abstract. Even “small” choices—like which transfers to include when blocks are full—can create a pattern: some users land smoothly, while others arrive late.
Fee design sits on top of this power. Plasma mentions stablecoin-first gas and even gasless USDT transfers. That’s interesting, but it raises a plain question: if users aren’t paying gas in the usual way, who is paying somewhere else? Fees are not only revenue; they are congestion control. If there is any way to pay for priority, the system is deciding who can buy the front of the line, and who must accept the back.
This is where mempools and relays matter. A public mempool makes intentions visible, which makes copying and racing easier. Private routing is often framed as protection: hide the transaction so it can’t be exploited. But private routing also becomes a gate. If order flow is private, it doesn’t become neutral—it becomes controlled by whoever runs the relay and sets access terms.
Now imagine two users. One is a retail user sending stablecoins through a common wallet. The other is a business using custom infrastructure and private submission. Even if both are honest, the default winners are predictable. The sophisticated user gets better inclusion and fewer surprises because they are closer to the pipe. The retail user gets the path their app provides, and learns the hidden rules after a bad experience.
Accountability is the next risk. If a transfer is delayed, reordered, or fails to land, where does the user point? The chain, the relay, the wallet, the infrastructure provider, or the app’s support chat? In payments, people don’t experience “layers.” They experience success or failure at a moment that matters. If the system says “finality is fast,” but inclusion depends on private channels and decisions, then “fast” is not the same as “reliable.”
This also changes what “fairness” means. In trading, some accept MEV as a market tax. But stablecoin settlement is closer to plumbing than to a casino. People want predictable fees and timing. If Plasma wants to serve retail and institutions, the question is not only “can it be fast,” but “can it stay boring under stress.” Boring means a surge doesn’t quietly turn into a pay-to-play auction, and ordinary transfers don’t become leftovers.
So the serious questions are not hostile; they are hygiene. Is ordering policy explicit and testable, or mostly “best effort”? Are there guardrails against censorship or preferential inclusion by leaders? If private mempools exist, who gets access, and on what terms? If relays become important, are they diverse and replaceable, or do they become choke points? When something breaks, is disclosure clear and responsibility owned, or does it dissolve into “that’s just blockchain”?
I also think about what incentives tell validators and proposers to do. If MEV is available, it will be pursued—not because people are evil, but because systems pay for it. If the design leaves a wide MEV surface, the network is effectively paying leaders to extract value from ordering. If the design tries to reduce that surface, it has to do so intentionally, with constraints that still work under load.
None of this is a verdict on Plasma. It’s a mirror for what stablecoin settlement really demands. Fast finality is one sentence. That sentence matters less than the next: fast for whom, fair by what rules, and predictable under what pressure? If ordering and fee incentives make certain people win by default, is that the settlement layer we really meant to build?
