I find that a lot of junior developers tend to go overboard with creating small functions, and the motivation is largely aesthetic. They have a mental image of what “clean” code is supposed to look like, and it doesn’t involve lots of indentation, curly braces, mathematical notation, etc. So they often try to bury these messy details inside a function.

They don’t have a lot of experience reading and debugging other peoples’ code, so they might not consider how much of a pain it can be to have to go jumping through a whole bunch of deeply nested one or two-liner functions just to see what the code actually does.