When you write an async. server in C++, where you can't inline functions, you write functions like OnRead(), OnWrite(), etc. Once you get used to it the whole thing ends up fairly easy to read and understand. Eg.

https://github.com/scalien/scaliendb/blob/master/src/Framewo...

I guess the OP is saying inlining [in a language where this is even possible] leads to unreadable code, which sounds about right.