I think it's still an important clarification, because for years you've had a choice in RDS (classic RDS, not Aurora) between "single-AZ" and "multi-AZ" instances, with the general rule of thumb that production workloads should always be multi-AZ.
however, "multi-AZ" has been made ambiguous, because there are now multi-AZ instances and multi-AZ clusters.
...and your multi-AZ "instance", despite being not a multi-AZ "cluster" from AWS's perspective, is still two nodes that are "clustered" together and treated as one logical database from the client connection perspective.
see [0] and scroll down to the "availability and durability" screenshot for an example.
> We show that Amazon RDS for PostgreSQL multi-AZ clusters violate Snapshot Isolation
you kind of have to expect people to read