I also enjoyed the Quora digests until one day the links stopped going directly to the threads but all pointed to a feed page. I assumed this was another dark pattern to boost pageviews and unsubscribed.
I prefer the feed page. There's usually more than one interesting link in a Digest and the pages aren't exactly lightweight on my phone. I wouldn't be so quick to call it a dark pattern; could be a reasonable UX decision based on how people use the emails.
Relevant to this thread, since the goats-vs-sheep study is brought up so often to add authority to the claim, Caspersen et al. were not able to repeat Bornat & Dehnadi's results. They discuss their findings here: http://dl.acm.org/citation.cfm?id=1268845
I'm not color blind, but I see the same thing. Shading creates the effect of the boxes being different sizes even though they're not. Here's a screenshot:
