When I saw the tweet by NCA, I too thought it was misleading, but clearly the author of that article, Aled Treherne, has thought about it a lot more and has some experience in this area. He makes a lot of sense.
This is basically the same crap story that was trotted out when we met with the home office, and I find it shocking that it is still being pushed as if it made sense.
They also have a slightly different info-graphic (the one in blue) which is very nearly the same and full of exactly the same holes.
Finding which on-line services have been accessed is somewhat pointless - for a start, if an Apple phone, then it will be Apple, and almost certainly FaceBook, Twitter, and WhatsApp. There are only a few major on-line services that a kid might be accessing, and asking the parents and friends will get a lot more information a lot more quickly that waiting to convince a judge to order a foreign social media or messaging service to hand over information and hoping they comply.
They talk of linking actions to devices? Well, what action? having a FaceBook account? Basically, any social media or messaging service will have permanent connections and regular traffic regardless of "usage" or "actions", so Internet Connection Records tell you very little - you can probably link half the smart phones in they country to FaceBook - this helps you how exactly?
The very nature of social media is that people share things with their friends, so ask their friends what is going on - there may not even be an actual crime!