When considering the TOS dedication plague, one should keep in mind that in TOS, the term "starship" was used to describe that specific class and its capabilities, and wasn't a generic term applied to all FTL vessels. It's possible that the term "Constitution-class" was retroactively applied in-continuity, when more classes came along that fit TOS's idea of a true "starship"...making the term "starship" descriptive of a general type of ship, like "aircraft carrier" or "battleship".
An interesting theory if not for the fact that it's based on a faulty premise.
MENDEZ: Inspection tour of a cadet vessel. Old Class J starship. One of the baffle plates ruptured.
The Menagerie - Part 1