You're looking at the docs for "visibility". Visibility is a separate eventually-consistent data store off to the side that's used for certain queries so it can be scaled independently of the main data store, and indexed in fancier ways. The main data store for all the stateful and transactional stuff has always, and probably will always, support Cassandra. For visibility, the recommendation for high scalability is currently Elasticsearch.
Temporal may have properties that make it not a good fit for a particular use case, but scalability is really not one.
Temporal may have properties that make it not a good fit for a particular use case, but scalability is really not one.