Database management tasks definition for multiple db in a remote connection context

Question

This section of the rails guides states:

If you would like to connect to an external database without any database management tasks such as schema management, migrations, seeds, etc.   [...]  

database_tasks: false 

is unclear to this reader.

On one extreme this means reading is connecting without managing the db.
On the other: migrations, seeding (and probably tests) are not.

But in the middle, writing to a database could be subjectively debated as being database management.

While I understand Rails sets out to manage main databases for writing and replicas for reading

connects_to database: { writing: :mains, reading: :mains_replica }

What about the use case of having an application that is distributed, but needs a centralised database servicing, say users, and this need to connect to read, write remotely and thus setting up in database.yml a

host: some-remote-db.domain.com

for that purpose? or is mutiple databases hard-wired for replicas (while the rails guide is somewhat opaque about this, I do not believe so as that would negate the need for a section on automated role switching)

Thus:

1. does database_tasks: false allow creating or editing records
2. how are the database_tasks specifically defined?