if you have valid proof they flag then I'd love to see it, otherwise again it's misinformation
I'm aware you wouldn't get instabanned, that would be extremely stupid on Jagex's part.
And you wouldn't get banned per se either.
They can flag an IP and have their detection software run with those IPs as priority.
Obviously I have no proof, I don't work with Jagex, but neither do you. Based on multiple experiences with botting from the same IP and computer it's safe to assume that such a system exists. Both because it greatly benefits Jagex and their anti macroing advances and because it's an incredibly easy thing to set up. They'd be stupid not to have it.
And I'm not the only one that considers this a valid theory, as made obvious by previous posters on this thread.
I'd like to emphasize though that this doesn't mean every account will be banned on your IP or MAC address, but it does mean your system might be prioritized in the search of bots.