I chose the Medicine project because it is an example where they have identified an issue (bad sourcing can have real world consequence) and built on the Wikipedia sourcing policies to fit with how medicine operates academically.

I imagine an interesting benefit with Wikipedia/History is that you don't run experiments, so of course much of the material you find is technically a secondary source; you thereby don't actually find the usual discussion of "primary" vs. "secondary" in this essay: "primary" gets defined as the actual source documents, as arguably history is all opinion ;P.

Absolutely this! And outside of science this is how it almost always works. A journal article will 99% of the time be a secondary source.

I maintain that attending conferences and taking courses in the field is seemingly not something that Wikipedia would look favorably on.

It depends what the intended outcome is. Wikipedia deliberately pushes the idea that editors should not argue from the point of an expert - as such qualifications are impossible to prove, and other editors as badly placed to peer review your argument/work.

On the other hand training in your chosen topic is useful! I've attended a number of sessions organised by Wikimedia chapters which put Wikipedians together with, say, historians so they can collaborate and learn from each other.

sending people to conferences, teaching them more about historiography, and getting them access to more sources of research, are all ways to make people better at performing what Wikipedia continues to call "original research" (and clearly wants no part in).

I'm not sure I agree at all here. Anyone wishing to write about a topic should have a good understanding of it, an understanding of research and citation and so forth. So those skills would be encouraged! (as an aside; it is this skill deficit that puts many Wikipedians off and ties back into the decline the article mentions)

Original research is another matter, unrelated to tracking down source material and understanding context.

Put differently, the goal of these activities is to make people better at interpreting primary information, not copy/pasting secondary information.

Again I disagree. Wikipedia doesn't want editors interpreting sources, but it also doesn't want blind copy/paste. Writing tertiary articles requires us to maintain an objective view of the material and to have good editorial judgement in choosing how to summarise the topic. The point of "no original research" is to stop Wikipedians inserting their own views or conclusions - so long as a view we record can be verified in a source and is balanced within the context of the article/topic then that meets this rule.

To put it another way. Writing a tertiary article often requires extensive skill in researching the secondary material, summarising the academic consensus on the topic and making sure that summary is objective and unbiased by your own views. The key word in "no original research" is original :)

The problem of primary versus secondary sourcing is one that is not even well understood by a lot of editors - so it is no wonder it gets questioned. But in practice the policy is trying to avoid the situation where Wikipedians themselves research primary sources to draw their own (often non-expert) conclusions. Therefore avoiding material subjective to an individual editor.

A core problem that does exist is that outside of science and history there is often a strong reliance of media reporting. And scholarly literature either doesn't exist for that topic, or is rudimentary (I mean, who is going to write a scholarly article about Justin Beiber). Policies that allow modern-style sourcing for such articles but also strongly favour scholarly material when it is available are hard to write :)