Earlier quoted context omitted.
Give them a working 8-bit system with hundreds of games and apps from the days before the Internet. There is still just as much working 8-bit and non-Internet software out there as there ever was: you just have to find the hardware. Then, most important of all: don't leave them alone with it. Stay there and play with them. Maybe you'll enjoy a return to the 8-bit software development days too, just for the heck of it…
Attempts to reason with them or ban internet have just met with stroppiness. Its like they have moved from being creators to being consumers.
My parents had limits on consumer computer/TV time when I was growing up (interestingly, both drew from the same pool of time even before internet TV was A Thing). If I wanted to hop on the computer, I'd always get asked what I was planning on doing with it (and then they'd drop by the computer station later to check in on whether I was actually doing that). If I was doing something educational, like reading up on a hobby, doing schoolwork, or programming, then I wouldn't be subject to any screen-time restrictions (other than those that came with it being a shared computer).
Though to a certain extent, kids just get stroppy if they don't get their way, and sometimes they just need to learn to deal. Which sucks for everyone involved in the short-term, but oh well. :/