Yeah, the websites/apps were the different front ends. But you were still streaming HBO. The movies and shows were the same, and if you had one it would be redundant to get the other. Max was introduced as an expanded library for Now, but eventually replaced both and Go was discontinued.
Streaming apps have their own catalogs and backends (although most of them license “all the music”).
You’re right, but I would wager they thought that statement was too stupid to be considered a reason.