Affiliate links primarily work through tracking hyperlink clicks within an article and monetising off the conversion rate. So for example right now, if you bought this sofa, I’d make a fiver. Go on, please buy that sofa. It’s a much more native way to monetise and is more congruent with the personal anti-salesman blogging culture. From speaking to bloggers I gather that this is quite a popular method of monetisation and they like being able to chose the links they feature and the companies / brands they support. But manually finding, implementing and tracking the links is definitely a time consuming process. And the more time and effort something takes, the higher the pay-off has to be for it to be worthwhile.