It's likely changed because the EU are introducing a new regulation on the 25th of May called the GDPR (General Data Protection Regulation). All companies which want to function in any EU member state now have to abide by the regulation. It's being introduced because currently there are no general rules for data protection across the EU, instead it's left up to the member states to regulate on it (which has caused issues in the past when people are living in one member state, but their data is being controlled/processed in another member state). The regulation covers a LOT of things, but I would speculate that them making game stats friends only is in order to cover themselves in the event that someone says that these stats come under the umbrella of 'personal data', which they would probably be correct in saying. The gist of the regulation is that the user has to be given the ultimate control of their data, and the company controlling or processing the data can no longer automatically opt people in, or have their opt-ins included in other terms like T&Cs when it comes to using their data in any way.
I've spent a decent amount of time reading the regulation in the past couple of months since it's cropped up in my classes, and in the solicitors firm that I had a a placement in. I can say that from what I've read and from what I've heard many other people say the regulation is and extremely good thing for the general consumer, and if I had to choose between this regulation being implemented or having my play time on steam games automatically shown to random people I think I'd choose the former every time.