I think part of the problem is imitating having abstraction boundaries without actually doing the work to make a clean abstraction. If you’re reading the source code of a function, the abstraction is failing.

The function calls you write will often “know too much,” depending on implementation details in a way that make the implementation harder to change. It’s okay if you can fix all the usages when needed.

Real abstraction boundaries are expensive and tend only to be done properly out of necessity. (browser API’s, Linux kernel interface.) If you’re reading a browser implementation instead of standards docs to write code then you’re doing it wrong since other browsers, or a new version of the same browser, may be different.

Having lots of fake abstraction boundaries adds obfuscation via indirection.