Comment by CyberDildonics

you need to know a priori which sub-scopes are independent and hence collapsible and which aren’t.

What does independent mean? I would just collapse them all because they were meant to be collapsed in the first place.

you have to analyze the unfamiliar code first in order to know which sub-scopes you might want to collapse

Unfamiliar? I wasn't refactoring and collapsed them all.

The benefit of extracted functions is that you know that they are independent of the implementation details of the caller (i.e. can’t possibly depend on or modify local variables of the caller other the ones passed as arguments).

That's true to an extent, but this is more of a way to make monolithic functions simple, which then makes the program simpler over all because you can avoid lots of tiny little functions. What you can end up with is programs that do non trivial things but don't have tons of functions confusing the issue.

Pragmatically this isn't really a problem. The whole "it isn't exactly a 1:1 replacement" isn't the point. You can still put in comments and const references if you really want to.

IDE affordances are fine, but I’m opposed to requiring reliance on them for reading and understanding code, as opposed to writing.

Why would it be required? The alternative is that you still have these commented sections with their own scope but they aren't collapsed. You can always work on it without the IDE and when you go back to the IDE it still works.

The reality of it is that you can see a broad overview of a function then see details one section at a time and you don't even have to go skipping around to other parts of the file or other files to do it.