Don't depend on others to ask for explanations

My opinion is that, in almost all scenarios, if you have a question, you should always ask it. Why?

1. If this question occurred to you, it probably has occurred to many other people. Thus, there is likely to be general interest.
2. The speaker (or author) has the opportunity to share more of his expertise, even if he is not about directly answering the question [this one is very underrated; I've had a lot of interesting conversations develop from seemingly foolish questions]
3. This gives the author the chance to explain his perspective more clearly. Your question may have implicit assumptions that the author rejects; this gives him the opportunity to state what his assumptions were (and thus, his frame of reference)
4. It allows a dialogue to happen between author and reader, which may result in even more insights (if you have a format in which this is allowed, such as a discussion board)
5. You will invariably have a slightly different perspective to the author. Two perspectives clashing result in interesting ideas
6. If the author forgot to write something down that he wanted to say, it gives him the opportunity to state that
7. The author may wrongly assume certain background knowledge. If your question indicates that his assumption was wrong, he has the opportunity to back up and explain it.
8. It makes the whole conversation a lot more interesting and engaging, it emboldens others to join it and contribute as well.
9. Foolish questions are especially useful, as they address the basic concepts of a subject. This is a lot more important than expert question if you want to get a coherent view of it.
10. The answer provided by the author will ALSO be helpful and beneficial to the other students / listeners / readers. By making him expand on his topic, you are benefiting everyone [also very underrated!]
11. Authors are often passionate about the topic they are writing or talking about. Giving them the opportunity to talk more about it, or to challenge them with difficult questions, or to ask things that they have never been asked before is something they, too, deeply appreciate.

As long as you stay within reasonable (context-dependent) limits (for example, you should not be the only one asking basic questions while everybody else looks bored) -- you should ALWAYS ask questions. It is definitely worth overcoming the fear of looking foolish. There is nothing more sad than somebody giving a talk and nobody asking follow-up questions. I mean, why not?

On the other end, when writing, I feel that recursively expanding upon your ideas to explain them and back them up is a skill that needs to be learned and practiced.

When I come up with an idea, I suspect that I do so with whatever abstractions and ideas my brain has on hand, but those are probably not the same as those of the target audience. When I start writing, I'll end up writing a ~1-2 sentence summary that I feel captures what I'm trying to get across. Then I need to make a conscious effort to unpack each of those component ideas and back them up with reasoning/examples to support my claims, this get's harder as I further unpack statements, because I'm more inclined to take those claims for granted. I suspect that this gets easier with practice, and that I'll be able to write progressively more detailed posts as time goes on.

Does anyone else feel that this is a bottleneck on their ability to explain things?

Even if there was no reluctance to asking questions on the part of the readership, the cost of the question-and-response loop would still be very high. For those who write due to a desire to move a group forwards, the following observations of mine may be motivating:

1. Each question consumes some of a limited supply of (something like) discussion threadcount and bandwidth, decreasing the range and depth of the consideration given the other aspects of a topic.

2. The resolution of each loop takes time; the full version of the original topic is not completely elaborated until later, in turn delaying the development of discussion based on the fully elaborated original topic.

3. The resolution of each loop takes time. In some cases, this means that people following a discussion ought to check in multiple times to stay up-to-date with an evolving explanation.

4. A question-and-explanation is (nearly) invariably longer and (usually) more time consuming to write than a (moderately) artful initial explanation... so a quickly written initial missive is usually false economy, even selfishly.

In a group with multiple productive members, #3 and #4, by increasing the time cost of staying abreast of the topic, may tend to decrease productivity.

(Ironically, my above explanations are too terse. My apologies.)

I think there is a trade-off as far as reader retention is concerned:

On the one hand, thorough explanations that the reader is already aware of can nevertheless give confidence to finish reading by signaling that the post is within grasp of the reader.

On the other hand, it is possible to overdo it and extend the length of the post beyond the attention span of many readers.

Speaking from personal experience, the high level of redundancy in many of Eliezer's sequences was actually very helpful for me to grasp and more importantly retain the insights conveyed.