At some point, a general purpose reference can get overwhelmed by specialized minutiae. I'm generally in the inclusionist camp with respect to Wikipedia, but I also don't think it's really an appropriate vessel for all of possible human knowledge. Which implies there is some line. So an article on the Big Dig is probably appropriate but not the blow by blow history of some country road.
Is the article on route 48 meant to be a 500,000 word treatise on its history including every work order involved in its construction and maintenance as well as discussion of the procurement process for the paints used for its lines, or can some of that maybe be elided? Would you expect the article on homeomorphisms to include a list of every homeomorphism every described, suggested, defined, or posited?
Wikipedia has a couple of devices to solve this organizational problem: "full article" links that appear at the top of sections, and "list of X" pages. So in your examples, you'd have a three-sentence "History" section on the Route 48 page, with a link to the full article on the history of Route 48 at the top. For your second example, there would be a "see also" section at the bottom of the article, including a hyperlink to "List of Homeomorphisms."
Risks of too much low interest data in wikipedia include:
* Not enough interest to update wiki when the subject changes; then wiki becomes out of date and unreliable.
* Too few eyeballs allows false information to be added (accidentally or intentionally)
* Becomes harder to do wiki-wide changes (of course it's inevitably too large for manual wiki-wide changes, but you can imagine more articles means more corner cases will be hit that will get automation mistakes or require more complex automation. Think info-boxes used in novel ways etc)
The first two are arguments against letting an individual write a single article about a unique topic, not against allowing a vibrant community of people with special interests document them in a public reference.
The third could be solved by only deleting pages that use the wiki language in unmaintainable ways.
A lot of making a high quality resource comes down to editing. Making sure you don't just include what you need but also remove what you don't. It is impossible to satisfy everyone, which is why i think it is a good thing to separate out to different resources when different groups want different things.
It's more the Wikipedia leadership that would have to be convinced. And looking at it that way, is it safe for all human knowledge to be gatekept by a single group?
I think the difficulty arises from finding a balance between a baseline that appeals to a general audience and an extensive repository for expert reference. Sifting through large Wikis can be daunting and discourage viewership. There is even an acronym for this: TL;DR
