Explaining something to someone else is a good way to understand and remember it better.

I think the key part of that sentence was "I'd like ..."

I can think of several reasons why someone might want to do such a thing.

• They want to begin or enhance a reputation for being an authority in the field.
• They want the organization that they represent to begin or enhance its reputation in the field and to popularize the particular spin that their organization places on such information.
• They are studying the field anyway, so the investment is essentially prettying up their own precis of materials they are reading anyway.
• They want to help the LW community and this is the way they choose to contribute. (For example, if there was interest in the field of law in which I specialize, I'd do the same, but I can;t see that fitting in here.)

Then, empirically, I note that people (who know these fields better than I) do actually post this kind of content here. But I don't see the karma system recognizing them for that contribution as much as being the "editor" of the whatever section would recognize them.

(Subsequently edited for terrible formatting)

Upon realizing this, the entire profession of journalism disappeared.