In this case it does by hitting hardware maximum. It scales until the max it is possible, due the bottleneck being in the hardware, not in the database or i/o. Check the article again:
> At maximum throughput, Postgres CPU is fully utilized, showing the database is actually saturated instead of bottlenecked on contention.
> At maximum throughput, Postgres CPU is fully utilized, showing the database is actually saturated instead of bottlenecked on contention.