I'm going to leave the fact that this seems like a rant aside and assume you're asking with the best intentions of the community in mind.
No we shouldn't close questions after one answer is given.
It explicitly states on the stats page for Area 51 sites
On a healthy site, questions receive multiple answers and the best answer is voted to the top.
SFF stats page - Note this is after beta graduation in 2012
So no we shouldn't close after an answer is given, as this would break the model of SE, which is to have multiple answers with the highest quality one (ideally) being voted to the top of it's thread.
No we shouldn't close it with the reason given.
If a set of answers do not fully address your question, please DO NOT ask a new question. We have a specific bounty reason for this scenario. A lot of duplicate questions are closed because they're slight variations on a question because the OP felt the answers given in the linked weren't sufficient at answering the question. If that is the case please use the bounty system
The current answers do not contain enough detail.
Bounty reasons and post notices - Stack Overflow Blog
As for: "[the proposal] seems to me to logically follow from the upvoted answer there (see the comments there at length)". It indeed only seems to you to follow. TheLethalCarrot had immediately rejected the proposal as absurd given the two are in no way identical.
That is of course not an equivalent example. – TheLethalCarrot 9 hours ago