Custom assertions use primitive comparison, not assertions

[Bananeweizen]

https://assertj.github.io/doc/#assertj-core-custom-assertions-creation shows how to create custom assertion classes. One part that I find very confusing is this piece of code in the custom hasName assertion implementation:

    // check assertion logic
    if (!Objects.equals(actual.getName(), name)) {
      failWithMessage("Expected character's name to be <%s> but was <%s>", name, actual.getName());
    }

I would expect to reuse existing String assertions there, e.g. to write this instead:

    // check assertion logic
    Assertions.assertThat(actual.getName)
        .withFailMessage(() -> "Expected character's name to be <%s> but was <%s>", name, actual.getName())
        .isEqualTo(name);

Is there a good reason to not use other existing assertions there (like confusing the logic to shorten stack traces or similar internal things)? If yes, can we please document it? Otherwise, shouldn't we change the example code?

I typically do use existing assertions in my own assertions, and I have this nagging feeling of doing something wrong without knowing what exactly. :)