Why is C# tuple notation not available for 1-tuples?

Question

Why is the easy tuple declaration syntax (int, double) t1 = (17, 3.14); not available for 1-tuple ?

CS8124 : Tuple must contain at least two elements seems odd when ValueTuple exists, isnt it ?

public class MyDict : Dictionary<(int a, int b), int> // ok
{
    public MyDict()
    {
        Add(new ValueTuple<int, int>(1, 2), 0);
    }
}

public class MyDict2 : Dictionary<(int a), int>  // Error CS8124 : Tuple must contain at least two elements.
{
}

public class MyDict3 : Dictionary<ValueTuple<int, int>, int> // ok
{
    public MyDict3()
    {
        Add((1, 2), 0);
    }
}

public class MyDict4 : Dictionary<ValueTuple<int>, int> // ok
{
    public MyDict4()
    {
        Add((1), 0); // Argument of type int is not assignable to parameter type System.ValueTuple<int>  
        Add(ValueTuple.Create(1), 0); // ok
    }
}