That wouldn't make much sense since the Reader interface requires []byte, but the specific connection could inherit WriterTo: https://golang.org/pkg/io/#WriterTo
I wasn't very clear. A hypothetical conn.Read(w Writer) would call Write on w instead of filling a byte array. Write in turn allocates as needed. WriterTo is a cleaner way of doing this.
> A hypothetical conn.Read(w Writer) would call Write on w instead of filling a byte array.
Yes I understand the purpose — hence suggesting WriterTo which is supposed to do that — I simply noted that conn.Read(w Writer) would make Conn not extend io.Reader anymore since it takes a buffer.