Most people resort to link selling because they have realized that PPC, CPM advertising is no longer lucrative for them because their Google adsense account has been disabled or other reasons.
Link selling is a high volume, low margin business and the link seller cannot afford to spend much money on the design and development of the website.
Some of the major webhosting brands in the US are extremely fussy about their clientele and will disable the account or delete files if the websites they host are not well designed. So the link seller will find that their websites are deleted without a valid reason causing a reduction in revenues . They will have to waste their time and money restoring the website repeatedly if they use reputed webhosting brands.
So domain investors who sell links or have private blog networks are advised not to purchase expensive webhosting as the reputed webhosting brands prefer well designed websites