Many of the features of modern programming languages are intended to supply tools which can be used to control this type of information complexity (for example, object oriented programming). They are indeed powerful tools and when used by experienced programmers who fully understand the theoretical background will do all that is desired. Unfortunately, many programmers assume that they can be correctly used without the necessary background knowledge: it like putting a Lamborghini in the hands of a newly licensed teenager. Expect a crash!
The programs on this website are really rather small compared with typical commercially useful software. Early examples make no use of more sophisticated methods, mainly because I do not want to confuse my readers. Somewhat later programs do use a few object-oriented techniques, but purely as a matter of minor convenience, and also to slowly introduce some of the methods into the mix. I know from my professional experience that a full-on OO approach can considerably confuse those who have not be trained to it.