Absolutely. But your expressions “must not create” and “we will not permit” (in recent post above) express a much stronger resistance to the idea of converting a virtual node into a real tiddler.
Author nodes in the biblio wiki are a nice clear illustration. The biblio wiki shows node for every author — initially by default a virtual node — offering an overview of everything in the wiki by that author. It could even tuck a top-image-result photo or wikipedia iframe (url constructed from author node name) into an html details element… all without there being a tiddler there! But of course you might at any point want to add specific biographical data or images directly at that author’s node, or override the default image/wikipedia url with one that works better for this author, or whatever.
Similarly with tag nodes. They should always provide a utility-like overview of what’s there under the tag as much as that can be reasonably anticipated to be useful (at a provisional tentative level) across the wiki. AND of course you might want to edit the tag node manually to manually assign a tag color or to manually order the list field, or to offer a description of what the tag means, etc.
My philosophy of virtual tiddlers (apart from the filter-expressions version) is: They anticipate exactly the kinds of things that you or your web visitors probably would want to see at that node, just insofar as any such info is already available (i.e., drawing on things that exist elsewhere in the wiki, or potentially beyond the wiki but still accessible to it, such as standardized web resources, mathematical facts, color swatches). This way, I rarely have to create a tiddler just to set up some template-like summary or “view from here” (of tag-children, or tiddlers with this fieldname, or this fieldvalue, etc.). I should only have to create a tiddler when I want to add substantive content.
(Occasionally, that new content will want to supercede the templated stuff. So I set up the “view from here” templates so that their display can be toggled off with a field setting. I’ve found such an override mechanism to be generally more useful than having any template that depends directly on the tiddler being “Missing”. Usually, we don’t want useful overview interface to evaporate just because the node-name is summoned into real-tiddler status in order to handle a list field or color value, etc.)
In sum (unlike Mohammad? and perhaps you?), I actually can’t imagine wanting to put anything in the story river that would NOT be (in principle) something I’m open to expanding upon through making it into a real tiddler.
Why would I ever want to prevent myself from adding onto on what an automatic virtual-node-oriented template displays (Let me jot something in its notes field, specify a class field, add a url link, or a tag, etc.)?
The exception “proves the rule” as they say: Filter-expression tiddlers nearly always contain characters that should not appear in tiddler titles, so they shoudn’t directly be converted into real tiddlers. But what I really should do is not simply to hide the edit button, but configure that “edit” button to open up a “Draft of” tiddler with an acceptable title (not the filter expression, but a streams-like unique string, or perhaps some RegExp-processed translation of the filter expression), and pre-fill its caption field with the filter expression string. “Saving” that tiddler would be a way of “writing to json” something that looks and functions as much as possible just like my otherwise virtual-only dynamic table overview of filter results, but now with additional content. Maybe I want a real tiddler there because I want to document this filter expression’s logic, or remind myself what role this filtered view plays in my workflow of maintaining and troubleshooting, or assign an $:/tags/AboveStory tag to this filter’s node, etc.)
I suspect any other use of “virtual tiddlers” — including those that call for a specialized name-space — either would still benefit from being creatable/convertible into real tiddlers OR they are so narrowly specialized that something like temporary (but real) state tiddlers would do just as well.