> and have to write a lot of additional code to do so. And most importantly: you have to read a lot of code like this, and understand it's assumptions, failure

> and have to write a lot of additional code to do so. And most importantly: you have to read a lot of code like this, and understand it's assumptions, failure modes, runtime behavior and bugs, which are different every time. Instead of just reading "ConcurrentHashMap", and be done with your day.