It's a known fact that Bluetooth shares the same 2.4GHz bandwidth that is used by legacy WiFi. It is also a known fact that USB 3.0 also operates in the 2.4GHz frequency range and, if cables are not properly shielded, will interfere with both legacy WiFi and Bluetooth communication. Further, there are many wireless devices - phones, intercoms, mice, keyboards, etc. - that also share the same bandwidth.
So, knowing all this, why do people continue to use legacy WIFi? Dual-band support - and the (very wide) 5.0GHz band - is the place to be and most routers have support for it using Wireless-N or (better) Wireless-AC communication. This will leave the 2.4GHz band for the lower-bandwidth devices (Bluetooth, etc.) to fight over.
You´re right, the keypoint is the shield of those transmitters, some laptops works well having both circuits running inside the equipment perfectly isolated nevertheless NUC NUC5i7RYH has both elements so close, in my case 50dBm of WiFi reception from the AP to NUC is not enough to avoid the noise coming from the Bluetooth next to the WiFi receiver into the box.