Actually, what Molot suggested seems to be that the recent Worldwide climate was related to (the first two words in Molot's comment were literally "Also related") Are single-biomed planets (like in Star Wars) possible? (itself a duplicate) and Single biome (hot) desert planet, possible?. Both Are single-biomed planets (like in Star Wars) possible? and Worldwide climate have been closed as duplicates of Are geographically typed planets realistic? Still closed as a duplicate, but not in the way you say in this meta question.
Now, with that aside out of the way...
Making a post community wiki is not a free pass for content that would otherwise be off topic or otherwise inappropriate on the site. From the edit community wiki privilege description page
Community wiki posts have been donated to the community in hopes that others will edit them to keep them up to date, to add useful information, and generally improve their quality.
Also compare the create wiki posts privilege description, which says:
Moderators can also choose to convert posts into community wiki mode if they feel it is appropriate for the question or answer, generally after a discussion with the community and affected individuals. Once a post is made community wiki, that mode can only be removed by a moderator under exceptional circumstances. Also see What are “Community Wiki” posts?
The linked Stack Overflow blog post (which, mind, was written already back in 2011) says, in part:
With suggested edits now in place, you could argue that the removal of reputation from voting is now the only function of community wiki. Unfortunately, this means it is often seen as a magic switch to allow questionable content.
Many sites propose using community wiki to allow content that is on-topic and useful, but can be considered borderline or questionable in other ways. Someone notes that a certain class of question has problems, and proposes using community wiki as a quick fix.
If a question is valuable enough that you believe it belongs on the site, chances are you don’t need it to be community wiki!
To me, all of this is really quite clear; community wiki is not a get-out-of-jail-free card and should not be treated as such. If the content is worth having, then it would probably be worth having even if community wiki wasn't a thing at all. A good question that one might consider posting and answering in a community wiki format is probably equally askable and answerable without community wiki.
Community wiki removes one of the major incentives to contribute on Stack Exchange — reputation points — and therefore risks to lower the incentive to contribute time and effort. Yes, those are just imaginary Internet points, but the things people do for imaginary Internet points...
That leaves the bigger issue, which is can we have a canonical duplicate target for questions that discuss the plausibility of single-biome worlds? To me, the answer to that is of course we can. It can even have multiple answers. If you think you can post a question that is (a) not itself a duplicate of the existing questions, (b) specific and narrow enough to be answerable in the question and answers format, and (c) on topic, then by all means go ahead! There isn't even anything preventing you from, in the question or in an answer, referring to, and quoting from, other, existing questions and their answers, as long as you attribute those parts properly. (CC-BY-SA encourages remixing.)
It seems more likely to me, though, that a set of questions discussing various aspects of such a world, or a few different types of such worlds (desert vs jungle vs tundra vs ocean vs whatever else one might come up with) would be more useful. We almost certainly already have a number of these.
To a new user, or a relatively new user, such as in the case of Worldwide climate, it really doesn't matter much whether their question is closed as a duplicate of a question with a community wiki answer, or of one where the answers aren't community wiki. At best, they are primarily interested in whether the duplicate target question actually covers the issue they are asking about. Being directed at a question that has community wiki answers doesn't gain them anything that a non-community-wiki post wouldn't be able to.
If a question is proposed as a duplicate of one that it is not, for some reason, then the proper course of action is for the original poster to edit their question to clarify how it is not a duplicate. Yes, this takes a bit of effort. But the process puts the onus on the OP to show why the community should spend the time to answer one more question, instead of just referring to the existing question and its answers. If even the person asking a question can't point to at least one reason why an existing question doesn't cover what they are asking about, then chances are it's close enough to provide a workable solution to their problem. They certainly can come back and ask further, more detailed questions about more specific issues.
Imagine if everyone who looked for something on Wikipedia would cause the creation of a new article that would need to be written, maintained and fact-checked. It would quickly become a complete and utter mess. For me, Stack Exchange shouldn't be treated differently; rather than duplicating effort, if the same question has been asked and answered, let's just point the new asker to the existing question and its answers (for which the Stack Exchange mechanism is to close as duplicate).
One guideline which I have referred to for a long time is Eric Raymond's How To Ask Questions The Smart Way. In this case, its Before You Ask section provides several hints: among other things, to search archives, search the Web, read the manual, read the FAQ, try to figure it out yourself, try asking a friend, and (for programmers with software problems) try looking at the source code. The vast majority of these apply equally well to asking worldbuilding questions on Stack Exchange. Also, to show what you've learned by doing all this. (Stack Exchange sites tend to be a bit more lenient, but my experience is that questions showing that someone has at least tried themselves first are better received.)