Perhaps its an overstatement, but you have to recall that Google's "I'm feeling Lucky" button was designed to be the one page they had deduced you were looking for, their stretch goal, a results page with one link. The one they know you're looking for.
Now they have backed off on that, with reasoning that it is really not truly possible given that the search "Sony XBR TV" might be you are looking for the manual for the TV or to buy the TV or something which isn't known, but the goal is always to have the result you're looking for on the first page. That has been their target and promise for years.
So by creating a feature, and putting it into production, to "block sites" it suggests to me that they are saying "Hey, we know our algorithm is failing and we have given up (perhaps temporarily) trying to fix it. We know it will put sites you don't want to see into the first page. Here is a manual tool to weed those out."
It seems like something of a philosophy change at least. Perhaps Matt will chime in.
I got to be honest. Blocking sites doesn't seem to be working that well for you guys.
Look at this search - "how to get pregnant" - that exact phrase gets 550K searches on google a month. My wife and I did this search last week actually.
Blekko's top 3 results are 1. get-pregnant-guide.com which is an affiliate site that points to pregnancymiracle.com - one of those crappy ebook sites where they have a bunch of testimonials and ask for you to pay $39.95 for their guide, 2. a digg post that has 1 digg which points to a hubpages article that no longer exists, 3. purelyfitness.com/how-to-get-pregnant which is also an affiliate site that points to pregnancymiracle.com.
Google's top sites are the mayoclinic.com, mahalo.com, and howtogetpregnant.net. The least useful to me was howtogetpregnant.net, but they still gave a decent amount free advice. I actually found Mahalo to be the most informative which is blocked from your results. I find Calacanis just as annoying as everyone else, but this page was more beneficial to me than even the mayoclinic.
The suggested slashtag for [how to get pregnant] is /pregnancy ... those results are pretty nice, albeit less medically-focused than the /health results.
Now they have backed off on that, with reasoning that it is really not truly possible given that the search "Sony XBR TV" might be you are looking for the manual for the TV or to buy the TV or something which isn't known, but the goal is always to have the result you're looking for on the first page. That has been their target and promise for years.
So by creating a feature, and putting it into production, to "block sites" it suggests to me that they are saying "Hey, we know our algorithm is failing and we have given up (perhaps temporarily) trying to fix it. We know it will put sites you don't want to see into the first page. Here is a manual tool to weed those out."
It seems like something of a philosophy change at least. Perhaps Matt will chime in.