The general premise still holds though - As long as the pre-money in a round exceeds the post-money in the prior one, the owners are worth more. The analysis is over-simplified, but it still explains the situation clearly.

As for how much is given away... I think Cloudera is a special company. Most of the unicorns are. The same strength ("We can wait on the money") that gets them to a billion is also what allows them to get away with less dilution.