For some things, you need a "real" computer. For some things, you need a tablet ("LOL what could that possibly be?" Oh, I dunno, does your laptop have multiple

For some things, you need a "real" computer. For some things, you need a tablet ("LOL what could that possibly be?" Oh, I dunno, does your laptop have multiple very-high-quality cameras built-in with all kind of fancy depth-sensors and AR-related hardware, an accelerometer, et c.? GPS and/or cell radio? Touch & drawing input? Stupid-high idle battery life, with near-instant-on from any level of sleep? Sure, some have some of that, but how many have all, especially without peripherals? How comfortable is it to use while standing, or while walking around? How good's your laptop at replacing a scanner? Reading PDFs or ebooks while on the go?) The more things i-devices can do well-enough that were previously desktop- or laptop-only means more times you don't need to have both devices to be able to do all the things you want to do. It's harder to go the other way (making laptops/desktops good at the things tablets are good at—most of those require adding more, expensive hardware, and changing or hybridizing the form factor) so the trend is in the direction of making tablets more and more capable.