How are they ranking like this?

I recently hopped into a new niche and the site that ranks 1-3 for all of my targeted KWs does so like this:
https://freeimage.host/i/HFZVP2


That's almost 85% of their backlinks that are just images posted on PBNs.

This is what most of these actually look like on page:
https://freeimage.host/i/HFZXFS

Mostly small low quality images without context or text.

This is on what I consider medium difficulty KWs with thousands of searches. What gives?

Jimminy Christmas- those captures didn't show up. Sorry, those are screenshots.

...man always holding me down. #fightdapoweryo #metoo #hashtag


Anyhow, these are directly pointing to their affiliate site and their closest competitor on the same KWs are using the same bloody method too.

Simply linking some images on an unrelated site with zero content and walking away clean as a whistle.