@shazow.eth
Part of the narrative of this design is that it's up to the contract to shard and load balance accounts so they don't get impacted by load concentration.
In the case of a dex, each token pair could be a separate contract. But even thats not enough (top few token pairs get the vast majority of volume etc).
If you take it to the logical conclusion, it kinda starts to look like appchain rollups, where each rollup has their own metering.