Here's why:
* Linking verbs connect the subject of a sentence to a word or phrase that describes or renames the subject.
* Seem expresses a state of being or appearance.
For example:
* He seems happy. (Happy describes the subject "He")
* The sky seems blue. (Blue describes the subject "The sky")
* She seems like a good person. (A good person renames the subject "She")
Let me know if you'd like more examples or have any other questions!