Why four definitions of std.meta.Replace?

[Andrei Alexandrescu]

/**
  * Returns an `AliasSeq` created from TList with the first occurrence
  * of type T, if found, replaced with type U.
  */
template Replace(T, U, TList...)
{
     alias Replace = GenericReplace!(T, U, TList).result;
}

/// Ditto
template Replace(alias T, U, TList...)
{
     alias Replace = GenericReplace!(T, U, TList).result;
}

/// Ditto
template Replace(T, alias U, TList...)
{
     alias Replace = GenericReplace!(T, U, TList).result;
}

/// Ditto
template Replace(alias T, alias U, TList...)
{
     alias Replace = GenericReplace!(T, U, TList).result;
}

Why all this? Delete it, rename GenericReplace to Replace, and call it a 
day.

I reckon documentation won't be as nice because GenericReplace just 
takes an ellipsis? Was this the rationale? I don't think it's much of a 
problem, and if we decide it is, version(StdDdoc) takes care of that 
with less aggravation.

This pattern is all over std.meta, and it's bad.