Google cannot categorically ignore copyright claims without opening themselves up to potential legal liability. If you've made a hundred bogus copyright complaints to Google and they cut off your access, and you send in another complaint, they still have to either A) shove it into a DMCA safe-harbor exception, or B) risk knowingly continuing to violate your copyright. Option B is straight up not happening when the risk is that high, not without expensive lawyers reviewing the situation.

There isn't and will never be a "strikes" system for false copyright claims.

they can deny access to content ID, and require manually submitted claims (providing a postal address and requiring hard copy notifications still meets the DMCA requirement's AFAIK)

so while they cant just ignore a claim, they can make it harder to make a claim.