Captions are meant as guidance - to help players know where they can loot, craft or otherwise obtain Pets.
Seems like you're issue is with the use of the term "only," taking it to mean that there would be no exceptions for events like Egg'Zavier or Pet Rescue (which are advertised as offering access to literally every pet in the game).
We'll consider removing the term if it'll help but the word 'only' is used in dozens of descriptions to clarify that a given Egg or Pet isn't available from other sources.
Best wishes!
Bookmarks