It is not for protecting user secrets. It has nothing to do with users.
It is about protecting against "after hours" production runs. If you, as a vendor, order manufacturing 1000 pieces of widgets, you want to be sure that only those delivered to you are really produced. You don't want more, and then your own product competing against you on the market.
Hence, encryption. Only your devices can run your firmware. All those extras cannot.
Enjoy all the benefits of keeping stuff to yourself I guess.
Bonus: potentially lowers the barrier to entry to electronics fabrication as more engineer hours are spent getting the fabrication equipment/processes better documented/more accessible.
No one wants that though. That'd make too much sense.
It is about protecting against "after hours" production runs. If you, as a vendor, order manufacturing 1000 pieces of widgets, you want to be sure that only those delivered to you are really produced. You don't want more, and then your own product competing against you on the market.
Hence, encryption. Only your devices can run your firmware. All those extras cannot.