The best companies that realize this can minimize it, but its inevitable.
The virtual space is locked down so so so much harder than the physical because it's "free" to automate, but the vibe is it's outrageously uncontrollable. I get it when we're talking the whole Internet, but the same group of insiders?
Sure. But if that's the case why do you even have individual email? Make everything a group email and group IM. Not allowed to send messages to a specific person; can only send messages to everyone. What would happen?
Can you see the flaw in this logic? Email isn't only for discussing work projects. It needs to be private for discussions involving HR, legal, and other personnel matters.
I think your point would be better made if in your hypothetical, we still had individual mailboxes, but everyone could see into everyone else's mailbox.
Of course you likely had no immediate way to reply to an internet email address like that at the time out of the box.
You’ll have 1,000x more headaches and burned operational cash getting everyone to approve everyone else’s every step than handling one security incident in a decade. And even with very tight security, something will still happen. It’s best to have backups, a good restore plan, and a relaxed culture*. Or that’s what I think, anyway.
I’m in SME land though, not big tech. But then again, 99.99% companies are.
* common sense exceptions apply.