Simple answer to the OP is that Tim Apple & Friends decided to try and increase revenue by introducing a line that they hadn't fully thought out - the iPad Pro. Before that, we had one line of iPads that had cutting edge chips every year, one size and a clear enough purpose - a leisure device that sits in between the computer and the phone. All for $500 usd, which almost sounds too good to be true today.
In order to justify the increase the price, they put in whatever they could come up with - faster chips, the pencil, four speakers, true tone etc. Then the big one came out. And the keyboard accessories. And then, the new design came out, and with it, more "pro" features to justify a yet higher price tag. Notably, USB-C and a files app made it seem like it can do some of the things a normal computer can.
The latest one now has 1:1 hardware with current Macs. Even thunderbolt! They've kinda "pro'd" it into a corner by saying the Mac and iPadOS will not merge, but adding hardware and setting a price that would make people think that it can or should be a computer replacement. But they have no idea where this ship is going, they're just going with a wait-and-see approach.
I just think a real desktop browser and decent files app would alleviate 80% of the complaints people have.