Earlier quoted context omitted.
You can block any source you want. I have many sources blocked (ie TechCrunch) and others favorited (ie Verge). Just go to settings.
Where? I clicked the gear icon and there's a section called "adjust sources" but it just has a text box with a plus icon next to it. I tried "adding" wsj.com in the hope I could block it after adding but nothing happens after I click the plus button. It's a pretty confounding UI really. It makes me feel lost and confused and bad about my life in general ... :-(
When you click the plus button to add a source, it should show a bar bellow it with a slider of how much you want from that source. So you just slide it to the minus side if you never wanna see that, or to the plus side if you wanna see it more often.
If you're not seeing that, maybe something is wrong with your browser, try changing browsers or stopping extensions.