What are we talking about?
As long as there have been different languages, there have been second language learners. Likewise, as long as people have studied history as it is written, the tradition of philology has existed— generations of writers have had to work with the differences between their language use and the language use of those from other times and places whose writings they engage.
Linguistics is a relatively new field of study, calling itself the "science of language". As the types of studies that fall under the umbrella of linguistics are broad in scope and nature it would be unfair to categorize linguistics as a whole as scientism. Unfortunately, we see many people using the pedestal of being "scientific" to bolster their own particular views of language—and by extension push their ideas about anthropology, psychology, and even spirtuality and morality as given.
My own views on language proceed from a rather "traditionalist" view—languages are many, like species of plants and animals. Within languages we can observe changes over time, just as we can see families growing stronger or becoming weaker. Insofar as a families or cultures can standardize their traditions and make sure all their members possess certain knowledge of signs, so we see the homogeneity or heterogeneity of language. All (natural) languages have mechanisms for expressing what is shared by all humans—but they also have their differences as we observe differences between different groups of people. We don't call one language "better" than other generally, though certainly we can see how particular languages change shape to fit particular niches in the world.