The reason I would like to remove them is because they are problematic since one could pass them by simply doing the trick you already wrote:

     this.comparer.Equals(x, y);
     return true;

The assertions in the other tests are much stronger plus they setup stubs and also compare the expected result with the actual result. 

Applying the Devil's Advocate technique would be quite difficult, specially in the `EqualsReturnsCorrectResultForComplexClass` test, unless someone hard codes almost everything inside the Equals method.