Page "History of Esperanto" Paragraph 26

Esperanto has not fragmented into regional dialects through natural language use.

This may be because it is the language of daily communication for only a small minority of its speakers.

However at least three other factors work against dialects, namely the centripetal force of the Fundamento, the unifying influence of the Plena Vortaro and its successors, which exemplified usage from the works of Zamenhof and leading writers, and the transnational ambitions of the speech community itself.

Slang and jargon have developed to some extent, but such features interfere with universal communication – the whole point of Esperanto – and so have generally been avoided.