Final answer:
The main purpose of the speaker, considering the tone of the text, is to criticize and challenge conventional expectations.
Step-by-step explanation:
The main purpose of the speaker, considering the tone of the text, is to criticize. The tone of the text, as conveyed through the writer's language choices and use of rhetorical devices, indicates a critical attitude towards a particular topic or issue. The speaker wants to challenge conventional expectations and make the audience think critically about the subject being discussed.