In this case the main site is https://www.soup.io/ and the submitted story is to their news/blog site at kitchen.soup.io. Go to the main site and it is clear there what they do.
There is actually a link to that at kitchen.soup.io, but it is easy to miss. It's the small red circled "soup" in the very upper right.
I find it really annoying...
Also, it could just be the result of some bad ops/sysadmin decisions.
The simplicity of account registration, the possibility of creating sub-profiles within main one (similar to tumblr) were probably the sources of spambot thriving on soup. While we had post report and flagging features, only ignoring was the best way of getting rid of all that trash.
Tuning up the opportunity cost of spamming while making semi-targeted advertising more accessible and less obtrusive could tap into that market.