Ask HN: Why TechCrunch posts often do not make it to the front page of HN?

Agreeing with what the first comment said, but expressing the idea in different words, let's turn your question around and ask why TechCrunch posts should get to the front page?

A good-quality submission will be from a source with good content, close to original reporting of the facts, with some balance and sound judgment. Once in a while articles from TechCrunch fit those criteria, but much of the time there are better stories from better sources submitted to HN, and with luck of the draw in who is reading the new page at a given moment, generally better stories get upvoted, while average stories (frequent on TechCrunch) and below-average stories (not rare on TechCrunch) are ignored. I'm always looking for a pleasant surprise when I scan the new page

http://news.ycombinator.com/newest

(as I do several times each day) to look for stories to upvote. I try to submit stories that taught me something I didn't know before, as suggested in the Hacker News welcome letter.

http://ycombinator.com/newswelcome.html

TC used to be flavor of the month here (10 front page posts on any given day), but TC lost a lot of credibility after the CrunchPad fiasco and allegations that founder Michael Arrington had undeclared conflicts of interest in his reporting. After AOL acquired the business there was a conflict of personalities and Arrington left. Many people feel that what made the site's reporting distinctive and important went out the door with him.

This is where I go to find tech content and authors I wouldn't normally be exposed to.

If I wanted to read techcrunch, I'd go there.

They often do not make it to the front page because most of what TechCrunch write is just fluff, AOL likes to churn out the content at a ridiculous rate both in quantity and quality.

Most of the time when they do get to the front page it's because they're just pandering to YC or Apple fans.

Because TC is an "authority" on the subject and people like that. Let's say that I had submitted a post about black swans at the same time as that post from PG was submitted, then there's a higher probability that the post from PG would reach the front page because PG is an authority

Flooding the front page of HN with any single source would make it less useful. I like to see a variety of sources on HN. If I wanted to see most TechCrunch posts on the front page of HN, I'd subscribe to the RSS feed instead.

Because the most interesting information rises to the top. TechCrunch also seems to focus a lot on a small number of companies instead of more generally on interesting topics.

because the quality of the content, not the source, determine the number of upvote

To put it simply, it's because it sucks balls.