From The Federalist Paper No. 22 in 1787 penned by Alexander Hamilton
If a pertinacious minority can control the opinion of a majority, respecting the best mode of conducting it, the majority, in order that something may be done, must conform to the views of the minority; and thus the sense of the smaller number will overrule that of the greater, and give a tone to the national proceedings. Hence, tedious delays; continual negotiation and intrigue; contemptible compromises of the public good. And yet, in such a system, it is even happy when such compromises can take place: for upon some occasions things will not admit of accommodation; and then the measures of government must be injuriously suspended, or fatally defeated.
From The Federalist Paper No. 58 in 1788 by James Madison
In all cases where justice or the general good might require new laws to be passed, or active measures to be pursued, the fundamental principle of free government would be reversed. It would be no longer the majority that would rule: the power would be transferred to the minority. Were the defensive privilege limited to particular cases, an interested minority might take advantage of it to screen themselves from equitable sacrifices to the general weal, or, in particular emergencies, to extort unreasonable indulgences.
When you had Hamilton and Madison agreeing that it was bad for democracy, you know it’s fucking bad. Congress was never intended to operate on supermajority rule, take it from the guys who fucking wrote the constitution in the first place. The filibuster is an anti-democratic abomination.