Fundamental flaw in how BGP was designed from the old days. Give me a transit or peering connection where filters aren't in place, and you can announce anyone's IP blocks with their AS (SS7 is very similar, as it was built for a closed telcom ecosystem where all participants were trusted: https://www.youtube.com/watch?v=lQ0I5tl0YLY).
There are efforts to move to a more secure version of BGP, but that'll be done around the same time the transition to IPv6 is complete.
The problem is these kinds of leaks were more local except for services which have a large internal network. Yes - Google has that problem, but it is naive to assume that more of these won't happen. Any service which has a super easy path to having all their routing tables polluted so quickly is more vulnerable than others.
There are efforts to move to a more secure version of BGP, but that'll be done around the same time the transition to IPv6 is complete.