This is not true. Federal senators are elected on a state wide basis with the top N candidates past the post (N depending on size of the state). This can result in Senators being elected with a very small % of the overall votes.

For the lower house, we've had many years of the balance of power in the hands of a small number of independents who get an outsized voice.

Yes, if you live in an non-swing electorate, that is strongly held by the incumbent, then you could argue that your vote doesn't matter, but only because there are more people voting for something else. Isn't that how things are meant to work?