Why is this an issue?

Type parameters that aren’t used are dead code, which can only distract and possibly confuse developers during maintenance. Therefore, unused type parameters should be removed.

Noncompliant code example

public class MoreMath<T>   // Noncompliant; <T> is ignored
{
  public int Add<T>(int a, int b) // Noncompliant; <T> is ignored
  {
    return a + b;
  }
}

Compliant solution

public class MoreMath
{
  public int Add (int a, int b)
  {
    return a + b;
  }
}