I suspect that very few people even know about let alone use apps. Be interesting to see some figures but I've not come across any.
And I don't agree at all with the split screen thing being usable, it's clunky and restrictive.
People know about them, but I expect few people use them, due to comments seen in this thread, where people really are clueless and won't accept some apps are the best option.
As for split screen it's a extremely easy feature to use, and something I use every week, when copying one thing to another, usually some in for from PDF to excel. It is far easier than the split on the desktop and far more adjustable. And a thousand times easier than resizing windows. Although resizing windows is good sometimes when you want more control.
Why is there a need, because desktop software is not set up for modern day age, which is always on internet connection, and it really isn't a mess, it could be better, but it isn't a mess.
Unless syou run outlook/thunderbird, you should be using mail app. Nit only do you nit have to refresh several web paged emails, you get notifications (if you want them) and live tile. do you don't even need to refresh to see if you have mail. That's if you can even log into several emails at the same time, which you can't do if you have the same service, but several email addresses.
Things like eBay app is rubbish and I use the website, however I still have eBay app installed and logged in, to make use of the notification pop ups, so it notifies me when something i'm watching is about to end so I don't forget.
Things like news apps, general make more sense than websites. As you cam customise it, if you use an rss reader then this might be redundant.
Package tracker is a great app, granted Most people might not need it, but Ai order basically everything online. Not only fo Ai not need to go to a website and keeo finding the tracking number. The live tile as updates, when ever the package is tracked.
Again it's about using the best tool for the job, dismissing apps with out thinking about them really is limiting your experience needlessly.
Same token there's plenty which apps are crape for and I switch to desktop, which again is a single and instant key press.