I've toyed around with Kialo. Here are some thoughts about why it doesn't catch on:

• Argument mapping has disadvantages for politics and career-building. It doesn't allow the rhetoritician to slant the discussion, and it sharply limits the ability to gain credit by highlighting a point that's already been made, or restating it in a different way.
• The platforms themselves do a poor job of attracting eyeballs, so even if somebody did a great job of building up the Kialo form of some argument, it would go unappreciated.
• For those who take argument mapping seriously, we already have existing traditional forms that achieve much of the benefit of Kialo. The main benefit of Kialo is for helping amateurs and beginners navigate the complexities of an argument they're new to, but beginners and amateurs are those least likely to care about getting all the nuances of an argument.
• Kialo's short response format and lack of citations makes it hard to connect a point with a broader body of literature, and means that misunderstandings are likely.
• For those trying to use Kialo to understand an argument, it's a terribly unreliable resource.
• Kialo specifically makes it hard to figure out which arguments are important. I think there's not much signal in its voting mechanism for impact.
• It's less pleasant to read argumentation on Kialo than in a more traditional format.
• The amount of objections is overwhelming in some cases, while other arguments are missing.

For the future, I expect that additional objections will come to the fore, such as ChatGPT and other LLMs being able to produce personalized sets of arguments and counterarguments based on natural language prompts (which it can already do to some extent).

It seems very plausible that the straightforward explanation you point to is true, because people aren't aware of it, and they haven't had the usefulness of the method explained. 

Rationalists do a lot of argument mapping under the label double crux (and similar derivative names: crux-mapping). I would even argue that double crux approach to argument mapping is better than the standard one, and rationalists integrate explicit argument mapping to their lives more than likely any other identifiable group.

Also: more argument mapping / double-cruxing / ... is currently unlikely to create more clarity around AI safety, because are constrained by Limits to Legibility, not by ability to map arguments.

I think what nuno is saying is true to an extent, more people would do argument mapping if they knew about it. I think another reason is that a lot of people are uncomfortable from a technical standpoint engaging with math/logic/proofs, so there is inherently more demand for prose because pretty much everyone who would engage would logic could also engage with prose but not the reverse.

It’s sorta like research papers vs the articles summarizing them. Usually an article that summarizes the paper in a low fidelity way has more demand (even ignoring the fact that it’s printed in a more read space). Of course, lots of research papers are written still. But professors aren’t really writing papers in response to the demand curve of the crowd. They might care but at the end of the day they are following the citation and job incentive gradients. Meanwhile the only incentive I am provided is internet points.

For instance, I posted a mathematical formalization of when to focus on trying to increase the quality of the future vs reduce x-risk. my intuition is that the post would have gotten (a bit) more engagement if I wrote it in prose, even though I think the value of the post is an oom+ higher in the way I wrote it.

Either way strong strong strong agree, writing and reading prose is not an effective way to do research at scale (or perhaps at all, but to a lesser degree).