You say this sarcastically, but it is actually true. A nil pointer is not useful. Once you have determined that a pointer is nil, you have confirmed that the function returning it at all was a waste of both space and time. Though it's actually only half true: nil pointers are worse than useless and they provide negative utility, because they allow invalid code to compile. A better design - which is also more efficient, even considering the overhead of tagged unions - is to not return the pointer/value at all if it would be useless. Other languages allow for this, even C does allow for it with manually tagged unions. Go is rather unique, especially among modern languages, in how it doesn't provide any mechanism for it, so people use what is available to emulate that.

For the rest of it, well, you've contorted yourself into some really interesting positions.