Some users were shut out of Google services briefly last week, when an Indonesian ISP misconfigured a router.
The Internet is a highly resilient system, having been designed originally for military purposes. A disruption like this is eventually routed around. However this incident and others like it, demonstrate how easily it can be broken for a time.
Although this wouldn’t cause permanent issues, a bad actor could use an attack like this to disrupt a site they are targeting. By planting bad information a site can not only be made unavailable, but the attacker could clone the targeted site (such as a banking site), and attempt to steal credentials from misdirected users. This is why SSL certificates are so important to verify, although they have their own issues.