How do satire and irony swift accomplish what a more conventional persuasive approach would not have accomplished (or had the same effect)?

Satire and irony helped Swift.

Explanation:

In 'A Modest Proposal' by 'Jonathan Swift', author creates satire and irony in his narration.

Swift uses dramatical irony by suggesting that Irish should sell their babies to the rich so that they can grow the economy of the country. He wants to show how ignorant the rich are about the condition of the poor Irish people. Persuasive approach would not have created this effect.

The text is so satirical that he believes that country will honor him by building his statue for his proposal.  

He creates irony by saying that new-born of a under-nourished poor mother will weigh twelve pounds. But in actual this is a good healthy baby. So, he is using satire in his argument to show the plight of the people. It makes the reader think about them.

yeah, i think its a good thing what do you think?