It is a self-regulating system, any interference will mess it up.
If we feel that language has been in steady decline for the last 100 years, perhaps we should examine what's been different for that 100 years.

Schools, that's what.

A hundred years ago, the majority of children received only modest schooling, and their language was subjected to only modest meddling (mostly stuff like not using the more effective words where the vicar could hear it).

Teachers do not understand language. They do not know how it or why it changes or how or why it remains the same. All they can do is meddle with it.

And that causes the language to respond in unpredictable ways.