Serializing Color, Vector3, Quaternion not working despite documentation

Unity documentation says this:
https://docs.unity3d.com/Manual/script-Serialization.html

However, when I try to serialize those types, I get this error:
SerializationException: Type 'UnityEngine.Color' in Assembly 'UnityEngine.CoreModule, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' is not marked as serializable.

This is when I define a class as System.Serializable and have a field in it:
[SerializeField]
public Color[] colors;

And then call BinaryFormatter.Serialize. I found another person who had the same issue: https://answers.unity.com/questions/1645980/cant-serialize-color-or-vector2.html (their answer was just, don't do it, serialize each float manually...but the documentation says it should work without that).

 

The article https://docs.unity3d.com/Manual/script-Serialization.html is about Unity's built in serialization mechanism.

BinaryFormatter is not Unity's built in serialization mechanism and it has entirely different rules.