Jargon emerges organically.

If someone uses a distinctive-enough phrase, and the listeners understand and find it useful, they'll repeat it in the future.

The more that it's repeated, the more that listeners are more likely to know what it means, and it grows and compounds.

In search engines, there are pipelines that detect that key phrases like [MDN] in many contexts should be interpreted like [site:developer.mozilla.org].

This is a kind of emergent jargon via an internet-scale process.