Here's the thing: I don't want to work in UTF8. I want to work in Unicode. Big difference. Because tracking the encoding of my strings would increase complexity. So at the earliest convenience, I validate my assumptions about encoding and let a lower layer handle it from then on.

I understand you're arguing about some sort of equivalency between byte-arrays and Unicode strings. Sure there are half-baked ways to do word-splitting on a byte-array. But why do you consider that a viable option? Under what circumstances would you do that?