Important factor to earn money on line is increasing the number of visitor to your affiliate site. Also you must to retain old visitors.
If you wanna retain your old visitors, you must blogging consistently and writing good content. In the end people visit your blog because of content not because of advertise.
Loyal visitor is visitor who visit your blog again and again.
Like I say before, loyal visitor visit blog because of good content.
The sad fact is that the small number of loyal visitor click on your Adsense and affiliate ads.
This is the reason why you need new visitor. Returning (loyal) visitor just read your blog for new post and information.
The most of new visitors reach blog while search some term on goole (my experience). And this is type of visitors which brings you money from Adsense and affiliate ads.
People that reached blog through Google or other browsers will check all blog include advertise on it. These are the people who will click on Adsense and affiliate ads. This people then become loyal visitor if they are satisfied with the content.
The loyal visitor is important, too. If you have a large number of loyal visitors and we use CPM affiliate you can earn a lot of money and there is a lot of comments, which also means interesting reading.
In the end
Briefly: both types of visitors are important.