The iPad is a million different things to a million different people. One user might use it for light entertainment, another writing, another for industrial applications and (if you're like me) for myriad tasks around a science laboratory.
The reason I need an iPad Pro is primarily the camera system and yes, the processor. I record a lot of experiments and being able to zoom out to the wide angle lens to fit more apparatus into view is crucial. I also make extensive use of the LiDAR scanner for site plans, technical drawing, scale references, topographical mapping and photogrammetry.
If I used a Macbook for all this I would also need to buy an extra $20k worth of kit and then faff around transferring data; with the iPad Pro I can record, edit, send, process and transform all the data on-device in a fraction of the time.