Bitcoin Core highlighted in its June 6, 2025 joint statement that efficient relay helps avoid DoS attacks and promotes decentralization

Quotes that support claims

predicting which transactions will be mined, which also serves to prevent denial-of-service (DoS) attacks.

The goals of transaction relay include: predicting what transactions will be mined (for example for fee estimation or fee bumping, but it is also the basis for many DoS protection strategies inside of node software); speeding up block propagation for the transactions we expect to be mined. Reduced latency helps prevent large miners from gaining unfair advantages; helping miners learn about fee-paying transactions (so they do not need to rely on out-of-band transaction submission schemes that undermine mining decentralization).