This may be an advantage of design patterns: that they allow for a sort of brevity of class structure. You can think "ok, that's just the Composite Pattern there", and store it as one token in your short-term memory. Or at least fewer tokens. If your language let you, for example, use the Composite Pattern as a first class feature without having to code it every time, I'd bet your program would be easier to load into your head than one where you've got your own, new and possibly buggy, implementation of the pattern.