The filibuster is by no means a byproduct of modern times. In fact, the parliamentary tool itself was created as an oversight.
When Congress was formed in 1789, the rules for both the House of Representatives and Senate were identical. Both allowed for a parliamentary move called a “previous question” motion, calling for a simple majority to end a debate. In 1805, when Vice President Aaron Burr was presiding over the Senate, Burr requested that senators revisit chamber rules and remove duplicative ones. The Senate then removed its “previous question” motion, thereby allowing for unlimited debate. Keep in mind that the chamber was only in its infancy and had not tested all of the parliamentary rules, including limitless debate because the members believed they had no choice but to vote once the discussion was complete.
It was not until March 1917, when President Woodrow Wilson called a special congressional session to modify the parliamentary rules for the chamber, that the Senate adopted Rule 22, the cloture motion (requiring a supermajority to end a filibuster), into its governing rules.
The majority several times in recent memory has threatened the constitutional option, also known as the “nuclear option,” as a way to undermine a minority filibuster. Typically, a cloture motion must be filed in order to end the debate on the floor. However, a senator can motion for a simple majority to make the decision. This request runs contradictory to parliamentary rules and the member presiding over the chamber must deny the motion. The first senator can then appeal the ruling to the chamber, which only requires a simple majority. If the floor rejects the ruling of the presiding member, there becomes a precedent that a supermajority is not needed for that specific type of motion. (This can be done in part, meaning that only certain types of filibusters can be ended with a simple majority or in whole).
When Senator Harry Reid (D-NV) and Senate Democrats went “nuclear” on November 21, this is precisely what they did. Here is the uncut footage of the floor session from C-SPAN. Beware, it’s an hour long.