The excerpt below is what type of paragraph?

Topical. The topic is books and this text only focuses on books.

I would say that people then like now did not like being mocked so that is a probable reason why he disguised his message about society so he wouldn't directly mock people but more importantly it probably is because Gulliver's Travels could be considered a satire and satire was developed to criticize the society or politics of the day but in an indirect way since freedom of speech was quite limited in the time of the kings' and queens' control of society.