Why learn the specialist’s language ?

Recently, I’ve started reading and trying to understand some pure mathematics – particularly the abstract algebra (Category theory). There was a question from someone asking why am I doing that to myself, instead of making “something useful”. I understood the question, given that I’m an engineer by training, so I’m used to applied mathematics, which has concrete uses. But I didn’t have an answer. So what’s the use of learning all the terminology and abstract concepts ?

Then I found this in Will Durant’s The Story of Philosophy:

[learn the specialist’s language], as the specialist had learned nature’s, in order to break down the barriers between knowledge and need, and find for new truths old terms that all literate people might understand.

For if the knowledge became too great for communication, it would degenerate into scholasticism, and the weak acceptance of authority; mankind would slip into a new age of faith, worshiping at a respectful distance its new priests; and civilization, which had hoped to raise itself upon education disseminated far and wide, would be left precariously based upon a technical erudition that had become the monopoly of an esoteric class monastically isolated from the world by the high birth rate of terminology.

I think that explains why I’m trying to learn the language of the specialists.