Overall I agree with your post. As someone who feels like they're getting a lot out of anki, a few quick notes on my experience with it (been using for ~15 months continuously now)

• The first 2-4 months of use for me were very difficult, and consisting mostly of making bad cards that didn't usefully cement knowledge. I quit (for about 6ish months each time) twice.
• Anki is much better suited to some knowledge domains than others. I think the classic example of this is language learning - many people undisputedly have a lot of success with srs in this domain.
• Your steelman of using anki to make concepts highly available is something I use it for. I've installed a number of triggers where starting to think down a certain line brings up "autocompletions" that point me in a useful direction.
• The common srs advice to understand before memorizing is absolutely true. Not to harp on the point, but don't underestimate the importance of this.
• I put key points of a lot of workflows into anki. I wasn't sure this was going to work out (and it didn't 100%, but I've fine tuned my process based on results), but it's been very valuable in reducing warm up times when getting back into workflows I used to do very regularly that I haven't need for 6-8 months.
• Finally, anki is absolutely the wrong knowledge store for a lot of stuff. While there are many facts I think I am saving on by spending ~5 minutes over my lifetime (at a slight discount, since anki cuts mostly into nonproductive time while lookups cut mostly into maximally productive time), most aren't. Computers enable big, searchable knowledge stores which is highly valuable. Evernote is in this category, although it didn't really appeal to me. Gmail archives are another example. I've been using and enjoying workflowy for this lately.

Well this turned into a wall of text, so I hope someone can get some benefit from it :)