Oh yes they are. It’s an everyday occurence to export a zone from one name server to standard “master zone file” format and then import that into another name server running some other software DNS implementation. Having a standardized file format for machine-readable DNS data is extremely useful.

It’s also used as an interchange format between people, so that people can talk about DNS data structure in technical detail without having to either send binary DNS data to each other or use some program-specific syntax, which might be misunderstood or be incomprehensible by users of some other program.

You might want to argue that it’s a bad format, and you should feel free to do that. However, to argue that the RFCs either are wrong and don’t exist, and the standard “master file” format somehow is some program-specific format, when the format is clearly and demonstrably used by most extant DNS servers (if only for import/export) and is useful for a number of things, is not productive discourse.