I think it does, though Wikipedia can probably withstand the problem more than most sites.
In the context of PageRank flow, I definitely agree, and that's where I think most "get stuck", but in the context of "overall value", which includes "trust" I think there's a distinct difference -- If you ask me to cite a source right now I don't have them in front of me, but in "one of those articles/posts" by someone like Rusty_Brick or Bill Slawski or even a MC/GoogleGuy comment or someone else "who really studies things / knows their stuff", I remember reading about a connection between where you link and "trust" relating to your site/page -- Linking to "depth" / "a trusted source" has essentially the opposite effect of linking to "bad neighbors" or "questionable areas".
So, from the overly discussed perspective of PageRank distribution
[which many seem to think is the be-all/end-all way to rank, even though the results indicate differently], then I'm with you, but from an overall ranking perspective, especially including "trust" and "not simply talking about a topic" but rather providing a "depth of information" on a topic, then I have to disagree a bit, because if you look at WikiPedia's pages, you
[or any reader] swill ee if a word/phrase can be further defined, it is, and if a source of information is not cited/linked they're asking for it to be.
They don't say, "If there are already 20 sources on this page and you have another complimentary/conflicting source for the edit made or information provided, please don't post or link it...", or, "If there are already N links on this page and there's another page defining the term/phrase used, it should not be linked" -- They're definitely linking to "definitions" and "expanded information" as well as trying to get sources cited and they're not "limiting" those expanded-definitions/sources as long as the definition/source is considered valid/reliable AFAIK. If you know differently, then please, let me know.
Bottom Line: They don't care as much about the "link weight/pr distribution" as most "SEOs" do
[or at lest seem to], because they're trying to be "usable and informative" rather than "SEOing for 2005 in an effort manipulate search engines to rank them the highest", imo.