The spammers are linking the content to blogspot blogs so that they can: 1. hide the referrer from their affiliate program (to prevent getting banned for spamming) 2. to utilize the temp increase in search engine rankings 3. save money on domains for one-off usage
Actually, in most cases, these reasons have little to do with it. For the most part, the pages are created on public sites because the links are spammed on social networks, and those networks quickly block postings with the same links over and over again. So, if you can create hundreds of different URLs with the same landing page, you can have hundreds of times the spam posts go through and not be blocked. Most of these guys don't bother with private domains because social networks will quickly issue a blanket block to all posts containing links to untrusted domains that have been reported to them for spam, but they will never issue a blanket block for a site like Github or Facebook. So the links last longer.
As to the specifics:
1) 1. hide the referrer from their affiliate program (to prevent getting banned for spamming). There are much easier and reliable ways to not only hide, but entirely change, the referer. See http://www.contentgeneration.org/cpa-redirector-2/
2)to utilize the temp increase in search engine rankings
These sites aren't meant for that. Whether they link from the landing page straight to the affiliate link, or they go to a lander that is used to change the referer, they don't care about the search rankings of the links.
Actually, in most cases, these reasons have little to do with it. For the most part, the pages are created on public sites because the links are spammed on social networks, and those networks quickly block postings with the same links over and over again. So, if you can create hundreds of different URLs with the same landing page, you can have hundreds of times the spam posts go through and not be blocked. Most of these guys don't bother with private domains because social networks will quickly issue a blanket block to all posts containing links to untrusted domains that have been reported to them for spam, but they will never issue a blanket block for a site like Github or Facebook. So the links last longer.
As to the specifics:
1) 1. hide the referrer from their affiliate program (to prevent getting banned for spamming). There are much easier and reliable ways to not only hide, but entirely change, the referer. See http://www.contentgeneration.org/cpa-redirector-2/
2)to utilize the temp increase in search engine rankings These sites aren't meant for that. Whether they link from the landing page straight to the affiliate link, or they go to a lander that is used to change the referer, they don't care about the search rankings of the links.