Allan Bloom wrote in 1987:

Freedom of thought and freedom of speech were proposed in theory, and in the practise of serious political reformers, in order to encourage the still voice of reason in a world that had always been dominated by fanaticisms and interests. How the freedom of thought and speech came to mean the special encouragement of and protection of fanaticism and interests is another of those miracles connected with the decay of the ideal of the rational political order. The authors of The Federalist hoped their scheme of government would result in the preponderance of reason and rational men in the United States. They were not particularly concerned with protecting eccentric or mad opinions or lifestyles. Such protection, which we now often regard as the Founders' central intention, is only an incidental result of the protection of reason, and it loses plausibility if reason is rejected. These authors did not respect the many religious faiths or desire diversity for its own sake. The existence of many sects was permitted only to prevent the emergence of a single dominant one. (The Closing of the American Mind - p216)

He was writing about America and its founding principals, but it applies to the freedoms that define democracy universally. Amongst "eccentric or mad opinions" the most regrettable are those that exploit these freedoms in order to promote their dismantling, or that use these freedoms to intimidate other voices.