Some days I agree with that sentiment. But then I remind myself that I treat my iPad as a task device. In this context, task and app are somewhat synonymous.
I've a short list of tasks:
Apple TV: for task "watch Apple TV+"
Safari: for task "surf internet"
Google Maps: for task "surf geography"
Animoog Z: for task "make music"
While for sure I would love ipadOS to be a real OS, as long as it's the best device for even one task that I do regularly, I'll probably keep buying new ipads - but generally only once every four years, as I get my boost for my tasks from new hardware.
But I'll probably never buy another. The OS is just too limiting.
Perhaps they'll eventually decide to let them run MacOS? (Seems like a no-brainer, at least when a keyboard case is in-use, but apparently not.)