To defend your point, section 5 only says a "master file is most often used". It does not require the use of a master file to load a zone. Further, in section 5.2, it says "when a master file is used to load a zone". This suggests there could be occasions when a master file is not used to load a zone, e.g., a zone transfer.

Correct me if I am wrong but I think one difference between tinydns and, say, nsd is that tinydns reads a zone file from disk to answer queries while nsd loads the entire file into memory. The whole "on-disk" concept seems a bit dated when one considers tinydns zone files are stored on mfs/tmpfs.

I still use tinydns (and cdb) heavily. I think it is well-suited for the home user. BIND OTOH is an ever-changing, relatively large amount of code to compile, a hybrid authoritative server/cache, and it comes with a sizeable amount of complexity. BSD developers have long been trying to replace it with something else like unbound. djb used to refer to "the BIND company" and I think that is a reasonably accurate description of its developers. Thankfully, djbdns is non-commercial. Its author does not try to earn a living by monitoring/manipulating other people's DNS use.