I think "misuse" is an exageration.  Various functions change some state and return a value that is usually ignored, e.g. os.umask(), signal.signal().

> Global variables usage is a pattern which might lead to code errors and many 
> developers discourage from following it.

What sort of code errors?  This really seems a stylistic point.  Maybe such developers would be happier using class methods and class variables rather than functions and globals variables.

Out of interest, what do you usually do in your initializer functions?