Wow this old chestnut again. Was DF's article marketing for Microsoft? No more so than their articles/speculation on PS4 Pro was for Sony, or their coverage after Sony's February 2013 PS4 reveal event, the only different being Microsoft gave DF exclusive advanced access and paid for it - which was fully disclosed:
This article aims to bring you the key Project Scorpio information, but we have learned much, much more about the hardware that we'll share with you as soon as possible. Microsoft invited Digital Foundry to visit the Xbox team at its Redmond HQ, paying for travel and accommodation.
Can you be paid to cover something and be retain your independence and journalistic integrity? Absolutely. Did the article come over as a bit gushing? In my view yes but XOX is powerful new console hardware, how can you be really interested in this stuff and not be excited by it, especially when you are among the first to see it up close outside of the company than made it!?!
I don't get it. I generally do think it was a bizarre way of revealing the specs, i.e. letting (and trusting) a third party to do it but whatever works. If Microsoft told DF was to write that would be different but I've seen no evidence of that.