What does "might as well have" mean?

Question

For all the ease in Carpenter’s response, Philbin might as well have told him that for a million dollars, he’d need to state his own name aloud or calculate the sum of one and one.

I know "might as well" is used to suggest doing something, often when there is nothing better to do.[1]

But I think "might" belongs to the structure "might + have + past participle" And we can rewrite the sentence in this way:

Carpenter answered so easily, as if Philbin might have told him that for a million dollars, he’d need to state his own name aloud or calculate the sum of one and one.

But I am not sure, so could you tell me what the meaning of the sentence above is?

The fuller text is:

Who Wants to Be a Millionaire is one of the most successful TV game shows in history. It’s also an excellent place to watch people grapple with disfluency— the experience of struggling to make sense of information. The show has more than a hundred international variants, but in each case contestants answer trivia questions that become increasingly difficult as they’re worth larger sums of money. Two of the U.S. show’s most famous contestants are John Carpenter and Ogi Ogas, who both walked away with impressive winnings. On November 19, 1999, Carpenter became the first contestant to win $1 million on the U.S. show. For the million-dollar question the show’s host Regis Philbin asked Carpenter which one of the following presidents appeared on the television show Laugh-In: Lyndon Johnson, Richard Nixon, Jimmy Carter, or Gerald Ford. Carpenter smiled briefly [...]

[then said] the U.S. president that appeared on Laugh-In is Richard Nixon. That’s my final answer.Carpenter was right, and he’d known the answer from the second he saw the question. The smirk that briefly crossed his face was the hallmark of fluent— smooth and effortless—mental processing. A small space in his longterm memory bank housed the link between Richard Nixon and Laugh-In, and the answer appeared to him without demanding much mental effort. For all the ease in Carpenter’s response, Philbin might as well have told him that for a million dollars, he’d need to state his own name aloud or calculate the sum of one and one. (Drunk Tank Pink by Adam Alter)

[1]https://dictionary.cambridge.org/dictionary/english/may-might-as-well

Answer 1

He does A. He might as well {do B}

Doing B would yield the same result as doing A.

He explained to the president why that course of action was a bad idea. He might as well have been talking to the wall.

The president heeded the advice as well as a wall would heed it.

I asked him to lend me his car. I might as well have asked him to give me a million dollars.

He was no more ready to lend me his car than give me a million dollars.

In your example, his ease in answering was so great, the questions might have been as simple as "What's your name?" or "What is one plus one?" The ease with which he answered would be the same.

He sight-read that difficult etude with such great ease, it might as well have been the tune to Three Blind Mice.

Answer 2

'May/might as well have done something' has the meaning that anything else would have been likely in yielding the same result as in the earlier case.

Here in this case the guest's requiescent attitude towards answering the question of million dollars seem to dispose the host to think this way.