Is it a waste of time? Only you can answer that. It depends what you want to use it for, and what value you get out of it.
I use remote_write from several satellite prometheus servers, to a central victoriametrics server with a longer retention period configured. It gives me a useful backup of the data, and a single place I can run queries with a global view. Also, if those queries are expensive, they don't affect the prometheus servers themselves.