Being a long time an active member of StackExchange sites here are some of my thoughts and added information that might be of value.
StackExchange sites focus on objective questions and answers and have an ethos unlike many other sites. The ethos is that questions need to be objective and sites have a currency based on votes which IMO is harmful.
The culture of a StackExchange site will have a large impact on people who rely on search engines for learning. By this I mean that StackExchange site Q&A tend to get higher rankings in Google and those learning will look at answers posted for learning. Thus people new to an area tend to get their first taste of a community from the StackExchange sites. Thus those that are active on such a site can have a large impact on the outward appearance of such a community. This can be a good or bad thing and only time will tell.
With regards to
StackExchange excels at organizing knowledge.
I have to fully disagree with that. For some sites, maybe, for some tags on some sites that have a subculture for that tag, maybe, but in general I see that the sites generate more noise than signal.
When StackExchange experimented with documentation (ref) it was a great move toward organizing knowledge but SE abandoned the experiment.
If you look at the Zulip chats, you will see that they are not very structured.
I think the reply to this is obvious, they are chat sites not textbooks. I would not expect the information to be well organized.
StackExchange is searchable a lot more easily than the Zulip chats.
Searchable yes, useful results, that is a hit or miss.
One of the StackOverflow tags I visit daily is the Prolog tag. Many learning Prolog start off learning about list and so ask questions about
list. The problem with relation to StackExchange (SE) is that many students use the site and teachers keep giving different problems needing the same basic understanding. Since the students either don't realize this or are to lazy to do basic search (research) they just post a question and wait for the answer. A few days ago I did a search of the Prolog tag with answers containing the word list and found 7,858 results. If we change the word
list to the tag list
[list] there are still 3,210 results.
StackExchange is more visible.
As I noted earlier that is true because Google gives SE sites a boost for page ranking. But as I also noted earlier, the site then becomes one of the main welcome mats to the community and that can be a good or bad thing. Since SE sites have some pretty serious constraints those constraints distort the true liveliness of the community.
- When looking at the points (used as a correlation of being new to SE) of recent followers the number of people with low counts I have to ask if this really a tool that they should have in their toolbox? As @Andrej notes
the very active Zulip instances (Lean Zulip, Coq Zulip, Agda Zulip, Isabelle Zulip)
there are already useful tools one can add to their tool box.
SE sites require one to earn points to gain privileges. Does the community for proof assistants need a gaming system to help in learning?
Having spent years on these SE sites one of the odd things one learns is that some of the most basic and easy questions earn the most points and some of the more advanced and time consuming answers get next to no points. Where is the physics in that?
SE sites all have moderators. The moderators can have a significant impact on the direction of a site and thus one of the welcome mats for the community. So if and when the site goes live, think seriously about who you would want to be the moderator. I am a admin with full moderator privileges for a Discourse site and while I have learned a lot from the experiences, it is not a privilege that should be granted lightly.
Some teachers forbid their students from using SE sites so the students create burn accounts (think burner phone) to ask the question. After the question is correctly answered they delete the question and thus it deletes the answer and the information is lost. This happens more often than many know.
In fact, is there the correct place to post rationale for a new site?
Many years ago I use to be active on this site (Area 51) so yes the Area 51 meta site is the correct place to post this. The other way to think about it is, where else would it go? There is no where else, this is the logical place. :)
I have quite the respect for @Andrej and even noted that one of his answers was the most useful information I have ever received in a SE answer. (ref) Also some of his code is the quite useful. (ref)