Me neither. It is one of the hangovers from using Sky Go engine. Virgin have a single stream on up to six devices on Sky Sports, but 2 streams on 5 devices for all other channels.
My opinion is that you should be able to stream twice per pass (with extra stream if you buy boost), so rather than been stuck with 2 streams if you have sports, hayu, cinema, entertainment and kids, you get up to 10 simultaneous streams. It’s not as if you pay less for multiple passes, so why should you get less streams. And as many devices as you can possibly use and as many changes as you want.
I have sports separate from cinema/entertainment as there isn’t much overlap in our house. Use Now TV sticks (with 30 minute pause) for sports with boost, and now have cinema/entertainment on fire TV sticks. Works out pretty well even with a few tablets and phones.