"More speech" works when the number of voices is limited to an actual number of people. The truth would eventually/inevitably drown out the conspiracies and disinformation. Now, with bots and social media's algorithmic amplification, the "amount of speech" a single person can contribute is unbounded, and bad actors are weaponizing the unlimited nature of speech to drown out the truth.

"More speech" is too simplistic to work in the modern world.