Computers crash all the time losing your data. You can multitask with iPad, Word auto saves on the iPad. I've never had an issues organizing my files on my iPad, that apps for that, several of them and best part is they sync files and organizing to my other devices. You clearly have never used an iPad...
I don't know what computers you have in mind, they simply don't crash on me. It's mostly programs that do crash and even they are not as frequently crashing as mobile apps, and they are prone to crashing when they are facing RAM limits. On top of that, if you switch to just one other app in multitasking which uses just enough RAM to wipe the memory of your other seemingly always autosaving app and after switching back just return to its start screen, finding out that it's actually not autosaving, you might understand why it's often downsized to being a toy. Being at the mercy of the respective developer of every single app you need to have a workaround for that problem is not something one can call professional. I have an iPad myself and I like how it's acting as a bridge device, but it stays that way for as long as its infrastructure behaves that way.
To sum things up, there are important things missing that most professional and casual users need a computer:
- a native (not 3PP) files system to access ANY resources (attached storage, network storage/NAS, folder and partition management; using keyboard shortcuts. You can't even access your Apple Time Capsule's files without 3PP apps.
- the ability to install software depending on the developer, rather than the opinion of the manufacturer of the OS (you simply enjoy not using Little Snitch, do yo you?)
- the ability to choose versions of the software you use, depending on your use case
- downloading without installing
- the ability to program apps or anything else, performing even more or less complex (interface) design projects, handling fonts, media assets, storage, peers and sharing or organizing the files and assets in a way that makes the work progress worthwhile, not to mention having to create literally complex results like a game as Battlefront II which is using two iterations of its engine in one game
While I do graphics design, I do not consider myself as a professional because for as long as complex work can be over your head and there's no such disgrace to language as a pro-professional, I'm just a mere user. Maybe not just a mainstream consumer, but certainly not a professional, but being called that just because I use select software which iPads cannot run is but a joke.