It's better than it used to be. Back in the mid-90s I was a newly-minted network engineer working in my first datacenter and we were all very excited about this

It's better than it used to be. Back in the mid-90s I was a newly-minted network engineer working in my first datacenter and we were all very excited about this new "BGP" technology... Fifteen minutes later, half of Fairfax County is stuck in a routing loop, and we're getting calls from NOCs as far away as London asking us what the f* we're doing to their traffic. That was the wild west: back then, a typo could (and sometimes did) actually take down The Internet. There's more filtering and checking and second-guessing today. But, ultimately, it's based on a web of trust model, you're right, with all the weaknesses that come with that.