The first example is three characters longer and dispatches methods under the hood. There could easily be a dozen do_thing, do_another_thing and do_something_else methods.

In the second example, we have only function application. Put a breakpoint or print statement into do_another_thing and it is sure to go off.

(do_another_thing could support OOP dispatch as a generic function. A generic function is still something that is called first then dispatches methods based on its arguments. E.g. in Common Lisp we can (trace do-another-thing) to trace the calls.)