Remind me, why do we need the filibuster?

I’ve been writing about Congress since the late 1980s, watching as filibusters in the Senate evolved from rare and usually doomed efforts by fringe factions into what they are today: a routine practice by whichever party is in the minority. Republicans and Democrats have put the legislative filibuster to a stress test over the past decade, exposing faults I’d been dismissive of before. (The filibuster has been nuked for judicial and executive branch nominees.)