It's true that they have a high volume of stories but those stories are:

1) Shown to a huge number of people. Their traffic, I'm sure, dwarfs HN's traffic.

2) They have an enormous amount of people subscribed via RSS who will be able to read the news at their leisure.

3) Their stories are also shared via Facebook, Google+, Twitter, you name it.

4) TC articles make their way to HN and Reddit as well, providing additional exposure.

The second page of TechCrunch will still provide you with more than enough eye balls.