The question “Does censorship destroy freedom?” is, of course, impossible to answer yes or no. Certainly censorship can be a tool of tyranny and oppression, as we are seeing in Myanmar and Hong Kong today. But in a society which strives to be “free,” if the censor respects his or her jurisdiction and acts as an instrument reflecting current standards and (perceived) values, then a particular act of censorship can be appropriate and harmless, at least in the long run. The wealthy and powerful tend to enjoy “more free speech” because they have the means to reach a wider audience with a bigger splash, of course.
Academics have written about the “tyranny of iambic pentameter” in English-language poetics, lasting till late in the 19th century. The expression is figurative, though, as there was no actual “tyranny”: only a centuries-old tradition of taste, a vogue, a zeitgeist. Gerard Manley Hopkins (b. 1844) is frequently credited with breaking through and “freeing” the metric line with his technique of “sprung rhythms.” But Emily Dickinson and Walt Whitman were writing outside of that tradition as early as the 1830s.
Today, many literary journals refuse to publish, and professors regularly tell their students not to write, rhymed or metric poetry. These practices, too, reflect a current zeitgeist. Still, I have noticed that when editors or poetry professors say “free verse,” they really mean “unrhymed, unmetric, and non-formal.” Verse that is not free to rhyme is not really free verse at all.