Over time in a project, "flexibility" often starts to become synonymous with bug-prone, and poor organization of classes/functions/data is another big killer. T

Over time in a project, "flexibility" often starts to become synonymous with bug-prone, and poor organization of classes/functions/data is another big killer. Three functions in different places doing almost the same thing but with unique quirks, and you being fairly new to the codebase don't know that any of them exist, so you write a fourth. Neither OO nor functional approaches solve this inherently, but the tools of OO provide some nice options. Just think about why you'd be using them for each case.