Earlier quoted context omitted.
The way people on YouTube get around the legal penalties for false DMCAs is simple: they don't file a DMCA request. There are several other mechanisms by which YouTube will gladly pull content: Content ID, contractual obligations, TOS violation, etc.
I still don't understand why Google went on the route of proactively removing content rather than reactively.
Content ID was born out of a desire to keep Viacom happy after Google got sued: https://en.wikipedia.org/wiki/Viacom_International_Inc._v._Y...