From the linked MS article:
We wanted to reduce delays in handoffs between developers and testers and focus on quality for all software created, so we combined the traditional developer and tester roles into one discipline: software engineers. Software engineers are now responsible for every aspect of making their features come to life and performing well in production. This does not mean testing was abandoned, quite the contrary. This meant testing and quality was everyone’s responsibility.
I would be interested to know how this worked out! Developers writing unit tests is one thing but making them do all testing sounds like a sure-fire way to lose good team members.