Just a feeling. It's really very hard to get major brands like Nike as advertisers on board. Why: they want a perfect environment. A positive one and a premium brand which fits to them and a great audience. And not to forget a HUGE reach. Once you have all of these PLUS contacts to the right media agencies then you get good deals based on CPM. The less you as a publisher can offer the more you end with CPC or even crappy CPA deals where you never know if the intermediate evades your commissions.

Just look around, usually advertisers pair themselves with publishers with a similar brand awareness and quality. Eg Nike or BMW won't advertise on Reddit or Facebbok because there would be a too strong asymmetry between advertisers' and publishers' brands. Nike and BMW would rather place and position themselves to eg the next James Bond movie from Sony (=> similar brand perception).

Reddit is the typical publisher that is avoided by a lot of major advertisers. The brand and the audience is maybe too heterogenous and inconsistent. While a sub like Photshopbattles might be positive and funny many other subs like Gonewild (which is huge btw) give Reddit a mixed perception. However, doing a deal with Viglink shows that they must have tried everything before (to get deals with major brands) but finally resigned and go now the affiliate path.

There is one good thing about affiliate marketing though: ad blockers do not harm your business.