The filibuster isn't part of the system; it's not even part of the law. It's just part of the rules that the Senate chose for their own internal procedures.

It's just another thing that means people don't face the consequences of their own actions. If the extremeness of the elected party is blocked by the filibuster then people are angry at things not changing and so go even more extreme.

A similar problem in the United States is the excessive amount of law making by the Judiciary. In most countries the Judicary doesn't' make law it just tells Parliament that they need to change the law. This again means the consequences of who you voted for are not faced.

The pressure builds till there's a breaking point.