What are the application scenarios for encryption?

[317787106]

I don’t quite understand the necessity for encryption and decryption. As in Blockchain, most are decentralized, transparent and verifiable. As described in doc: "Communication is encrypted, protecting topic searches and record lookups against passive observers". Can you explain it in detail? Does encrypt and decrypt only works in UDP but not TCP ? Is encryption and decryption necessary in synchronizing and broadcasting blocks and transactions?