I think with the right texts, a lot of material normally considered implausibly complicated for a given person to learn, could be learned. Not quickly, but eventually. The problem is that with more complicated or obscure topics, it's necessary to keep developing concepts that are not reflected in the learning material, so that the only practical way of going about learning them is for the reader to reconstruct them with non-original research (by doing exercises, inventing them first when they are not available).

For example, how long would it take to learn undergraduate physics without doing any exercises, or having/exercising ability to do them, instead reading endless descriptions of worked exercises; compared with doing/inventing exercises yourself? The latter puts the training data in your head in a more natural form, so learning happens faster. The former doesn't require ability to solve/invent exercises, but would probably take a lot more data to distill the same patterns. So I think in theory this should work, but might be orders of magnitude slower, and requires enormous amounts of training data being prepared by someone else. Probably secondary education teachers at ordinary schools have a better intuition for this.

• Can we abstract thoughts endlessly to get around our working memory limits?

At least for this the answer is certainly no. There is a fundamental upper limit to the possible information storage density of a unit of space-time