Which is something I don't understand, just separate the signal and give me a digital output from the monitor, why are monitors doing digital analog conversion for audio too, all of a sudden?
It was useful for me when I hooked my nephew's Nintendo Switch up to my computer monitor to let him play and then connected desktop speakers straight to the monitor.
There are usually different flavors of the same base-model. Some have speakers, other not. Not adding speakers, but leaving the rest ist just cheaper and more reliable than tinkering with every flavor for single features.