As a user without the create tag privilege, I need to be able to ask a new question which does not fit under any specific tag yet. Maybe I already know the answer, and I just want to contribute new stuff to the site. Such was the case for me recently when I tried to post a question and answer detailing how to get around a bug in my local power utility company's crappy customer billing web application. Many stack exchange sites require at least one tag. And you will surely be whipped with a cane by the mods if you simply pick some random tag and put it on there so the site will allow you to post. This puts the onus on the user to do research on the available tags (poring over pages and pages of tiny text on the screen).
This requirement right here will shut out 80% of users already. Is it appropriate friction ? No, I don't think so. Every time the user experiences pain and frustration bouncing off this wall and being unable to post, they are less likely to try again in the future. Its sadistic. That sadism not what you want for your website.
Many Stack Exchange sites have tags which are specifically designed to help ameliorate this problem, for example the "retag" tag on the Anime & Manga stack exchange or the "website" tag on the Web Applications stack exchange.
However these tags, while well-intentioned, completely miss the mark and do not actually help users, because they are not delivered to the user when needed. The user still has to learn how to scale this research-wall that you have placed in front of them.
As an aside -- having help pages is ok, and making sure that the text on the help pages is actually helpful is fine... but lets be real here. Most web users can't read. Or, its not that they can't read, its that they won't. Like Bartleby the Scrivener, they would prefer not to. So any solution which requires users to read, especially ACTIVELY read, like, go out and seek information (research) is going to fail over 80% of the time.
So what are we to do? I asked a moderator on the Web Applications stack exchange if they had any ability to customize the text on the question submission page for their specific Stack Exchange site.
I was wondering about this because if the text (preferably rich text / html) on the question submission page could be customized on a per-site basis, then the moderators could mention these 'catch-all' or 'overflow' tags for new users directly in context, thus eliminating the research-wall and giving the user exactly what they are looking for when they are looking for it.
For example, the moderator could place some text on the question submission page that says something like
<Site>! Are you a new user? If you aren't sure what tag to put on your post, please use the "
<catchall-tag-name>" tag. Thank you!
Bonus points if moderators can customize the error message that gets displayed when the user tries to submit a post with no tags on it. This would be even more "in context", and might win a web design award.
The moderator Rubén never answered my question about whether or not this was possible, however they did direct me here. So I am suspicious that perhaps what I am talking about is NOT possible for moderators to do right now. I think thats the real root of this issue.