This question should be asked to the parents who named them.
In fact, more and more Japanese people (especially women) have names with only kana and no Chinese characters.
1: Some people write and pronounce the Chinese characters of their real names to make it easier for everyone to read. Lin Yuan belongs to this category.
2: It’s not a stage name, it’s just fashionable. For example, Sakurai Satosu and Yamamoto Mari