I don't think they're saying they're doing batch size of 1, just giving performance expectations of user facing performance
100 tokens/s on the user's end, on a host that is batching requests, is very impressive.
With TensorRT-LLM + in-flight batching you can oversubscribe that one batch slot, by beginning to process request N+1 while finishing request N, which can help a lot at scale.
I suppose one could get decent utilization by prompt processing one user while generating tokens for another.