Author here, comments welcome.
About the "entrance fee": Do you really feel that the shorter version is more difficult for less-experienced devs to understand? The verbose version is unlikely to be easily understandable, in my opinion.
In general, I don't think that more lines of code make something more readable.
If anything, I think it would help to identify what assumptions are inherent in our code, and at least point to references for a "less-experienced dev" in the comments. A comment that said: "Hey you! This code uses promises, so if you don't know about those, check out this ref: [URL]", would be extremely helpful in this case.