The majority of people don't even care about Stage Manager, and wouldn't care about any sort of would-be macOS-interface clone either. And we're likely talking high 90+% numbers here. These people are never going to plug in anything into their iPad apart from the charger.Even if stage manager and iPad's more complicated multitasking features are better than nothing, I think more people would be far more comfortable with more of a desktop interface when they plug in a mouse/keyboard/monitor.
So the crowd you're actually addressing here is a niche minority, iPad-as-laptop-replacement fans/diehards/fantasizers