Mostly right but it has little to do with computers being “dumb”. It has more to do with predictability.

Protocols are simply the standards used in he communications, much like people have standards for post mail, shipping, etc: where to write the address, what ZIP codes mean, how to mark packages en route, etc. It’s not that people are “dumb” but it’s just far more efficient to have most packages marked in same “language”.

Sure, computers are “dumb” (and also universal) but that’s why programming languages exist, protocols are not quite as good example of that.