Implicit conversion doesn't work with Component. Is it bug?

With this class

 using UnityEngine;
 using System.Collections;
 
 public class TestCtor 
 {
     string mc;
     public TestCtor(string _mc)
     {
         mc=_mc;
         Debug.Log(this==null);
     }
     public static implicit operator string(TestCtor _ac)
     {
         return _ac.mc;
     }
     public static implicit operator TestCtor(string _mc)
     {
         return new TestCtor(_mc);
     }
 }

instructions

TestCtor tc="abc"; print(tc);

give me

TestCtor

When I inherit TestCtor from Component, I get

null

When I try to create a MonoBehaviour with new, the compiler throws errors. But it doesn't react to doing the same with Component.