Now, there's websites who do this (e.g. Reuters, NYT), and those who don't. (e.g. CNN, BBC). Doesn't seem to be something demographic, rather just a style preference tho it seems to me a bit of a Germanism. And there's websites who do something 'in between' and websites who capitalize even words as 'On', 'The', etc.
Is there a guideline to this of some sort and a reason why Atlas choses the current format?
I'd rather have the 'normal' form without the capitalization, but that's just a personal preferrence, not a request for a change.

I'd bet there's loads of people who prefer the current headline format.