Yeah, the content took a HARD turn to the left in the last few years. I don't remember it being anywhere near as political even as recently as 5yrs ago. That suggests either a dramatic change in audience, or some algorithmic change that pushed that content more. I'd love to know what actually happened.
Imgur changed hands, new owners took a more heavy handed approach with moderation policies, which removed NSFW-ish content, partly because they were deemed sexist, partly to appease advertisers and to make Appstore folks happy. This ultimately fostered the emergence of an insular, far-left leaning community.
It was always rather left but at least it was clever left. Now it may as well be copied from some octogenarian's Facebook profile. "Like THIS if you think Donald Trump should be in JAIL!"
Frankly, hearing grade-school versions of my own opinions parroted back at me ad nauseum is more annoying than if the posts were coming from other end of the spectrum. At least you can make a useful comment on something you disagree with. Now Imgur is all echo chamber all the time.
Five years ago I wasn't as left-leaning as I am now. Perhaps a majority of the users got older and followed a similar path? I wonder if it could've been subreddits like The_Donald being banned that caused an exodus, potentially driving away many or most of the right-leaning users who would get posted to /all.