It's also been used (by both sides) to block all kinds of other things, from tax cuts to tax hikes, debt ceiling increases, defense authorizations, New Deal legislation, and judicial appointees. As a Senator, President Obama even voted to filibuster John Roberts appointment, who was fairly universally seen as a highly competent, qualified nominee as Chief Justice. In short, the filibuster has been used for the purpose it was designed for (a check on majority power in the Senate, which was designed to be much more conservative than the house - whether you like it or not, it's reality), as well as a tool for partisans and racists to get what they want. So basically, like every rule or regulation ever formulated.