Second Endorsement here...

The FAA used to require spins for a PPL. Due to numerous fatal training accidents, they deleted that requirement except for CFI's.

Times change, people come and go, so at some point the powers-that-be at the FAA decided that maybe spin training was not such a bad idea after all. So what they did was left the existing regs in place (parachutes) but "reinterpreted" them to allow any CFI to give spin training to anyone without a 'chute. Spins are still not mandatory for pilot certs, but you can do them if you want (without parachutes with a CFI).

The legal premise is that any pilot at any level of certification might want to earn a CFI some day, so the training is legit under that exemption. There is no law that says you have to have a CPL or ATP before you conduct training towards an instructor rating.

They are safe enough without 'chutes...if you use the right airplane in the correct W&B envelope. A stock 172 will usually recover on it's own if you release the controls.