I am also good friends with one of the original Pinterest engs and that person defends it in the same, almost irrational, way, but I probably would too if my stock value depended on Pinterest being ingrained into Google search results.
... because you didn't read the description of the problem on the Reddit post.
The problem is that, even with a logged in Pinterest account, clicking on a Google image search result doesn't take you to the image. Sometimes the image will be on the page, but not always. Sometimes have to perform another search on Pinterest to find the item.
Here's an example where the image is below the fold. There are plenty where the image can't be found without a search on Pinterest.
I quite like the idea of Pinterest but the hyper-aggressive signup stuff (especially for mobile users) is really off-putting.
I was under the impression that the current X-Articles-Free implementation of newspaper paywalls everywhere was a Google-friendly compromise.
Sounds like they are to me.
It's not explicitly stated either way, but when people talk about "image results" it seems safe to assume they are taking about Google Image Search.
With Pinterest results this sometimes happens: https://imgur.com/a/ktyNG
But not always: https://imgur.com/a/RrjJG
Notice how in the second link Pinterest is asking me to log in, even though I am clearly already logged in.
However when I added Pinterest to my personal block list, I had to add: pinterest.com, .ie, .nz, .uk, .au, etc etc you get the idea.
It was actually that cancerous link spam behaviour that made me block them in the first place, as it diluted the quality of my Google results enough to force me into taking action.
I really feel bad for people who aren't savvy enough to know that blocking things like bad search result or advertisments is an option.
I disagree. Search engines are supposed to find _useful_ sites. Every time I have come across a Pinterest link, I have either been presented with the image devoid of context or (much more commonly) asked to log in and just been presented with a generic list of Pinterest images. That isn't useful (and in fact actively frustrates what I'm trying to do).
Edit: typo fix.
If you don't like the fact that Pinterest is a popular site, fair enough -- but that's a personal opinion, and it's not a good enough reason for Google or any other search engine to suppress Pinterest images in search results.