This happens because the USPTO has no incentive not to rubber-stamp everything that comes across their desks. For some time now, their position has been to accept claims at face value and let the courts (read: the taxpayers) deal with the fallout.
Hopefully that at least means it will be easy to overturn if they try to enforce the patent.
It's hard to escape the conclusion that they just couldn't be bothered.
As mentioned above, Final Rejection just means you have to pay more money to continue the patent prosecution. This is called a Request for Continued Examination. RCEs are common.
Generally, the initial filing fees provide for two rounds of examination -- a non-final rejection and then a final rejection.
If the applicant re-filed the same claims that were rejected in the final rejection (w/o amending them), the examiner can issue an immediate final rejection on a subsequent RCE if he disagrees with the argument the applicant might have supplied.
This patent is worthless and harmless.