Could it because many people are evaluating the community version of the database? The enterprise/Aura (cloud) is definitely designed to be more scalable
There's no clustering. There's no monitoring. The only user is admin.
But for the low, low, yearly price of half a million dollars you can get the very basics required to run reliable production workloads.
We only used the community version for dev, but even that could scale quite well for a single node on SSDs.
But we also spent a lot of time learning how to map our use case to it.