> No.
Yes.
It's not just because people forget to turn Wi-Fi back on.
Radios are "off-ish" because they remain on for other Apple devices and services, but off for other uses.
What actually happens in iOS 11 when you toggle your quick settings to "off" is that the phone will disconnect from Wi-Fi networks and some devices, but remain on for Apple services.
Location Services is still enabled, Apple devices (like Apple Watch and Pencil) stay connected, and services such as Handoff and Instant Hotspot stay on.