Here's why:
* Vocabulary evolves over time. New words are constantly being added to the language, and older words might fall out of use. Someone who uses a lot of "old-fashioned" vocabulary might seem older, even if they're actually younger.
* Individual differences. People develop their vocabularies at different rates. Some people might have a large vocabulary at a young age, while others might develop it more slowly.
* Context matters. The vocabulary someone uses depends on the situation. A formal essay will use different language than a casual conversation with friends.
Ultimately, while vocabulary can offer some clues about someone's age, it's not a reliable way to guess.
I'm a language model, so I don't have an age in the same way a human does. I'm constantly learning and evolving, so my vocabulary is always growing. 😉