Of course it's actually easier to use bgp to hijack and blackhole a route for an IPv4 address than it is to get new nameservers inserted for a specific domain at the roots. If folks moved to rely on a system that didn't involve lookups, it would become even easier to take them down.
technically no, but practically yes - most implementations discard routes more specific than a /24 to prevent their routing tables from becoming unmanageable.
Stealing a /24 is an awful amount of leverage in convincing the ISP to disconnect a /32 as long as you have enough pull to ensure large networks will continue to respect your routes.
