anyone who defends linguistic decay is an idiot. Language changing over time is a fact, but it is not inherently beneficial or harmful. The specific changes are what makes it beneficial or harmful. The norman conquest of britain created a uniquely flavorful language with lots of nuance that only a handful of other languages could match up to (greek, russian, etc) but there are also other languages that have objectively smaller conceptual bases and poorer articulability in their diction, with a greater frequency of lacunas, definitional isolates, and/or repetitious, obligatory phrasing. It is a fact that certain changes can make a language less intellectually capacitive than other languages.