Phones are for talking, navigating, and casual content consumption. Desktops (and laptops) are for actually getting things done. Both are useful, but the former is not a substitute for the latter.
Tablets are oversized phones that can't even phone. I don't see any use for them that isn't better served by something else. They'd actually be useful if they ran a desktop operating system, and some early ones did, but modern ones don't.
Tablets do have a singular purpose, being drawing.
Of course, most tablets that aren't specially built for it (or are from Apple) are terrible at it, but I definitely wouldn't want to draw on a phone or with a mouse.
I seem to recall there being purpose-built drawing tablets that are only drawing tablets, and act as a peripheral to a computer rather than a computer unto themselves. That sounds good on paper, since then you can still use the keyboard and mouse for everything other than drawing, but I've never used one, so I wouldn't know.
Also, there are laptops with touchscreens and full-range hinges. With that, you could do your drawing on an actual, fully-functional laptop. I haven't used one of those, either, though. I do have a laptop with a touchscreen, which could in theory be used for drawing, but it has a normal laptop hinge and can't be held like a tablet or paper notebook, so actually drawing on it is cumbersome at best.
I've used both, and I'll take an iPad over a wakom tablet for drawing any day. Every time I got an os update the tablet would stop working. I couldn't really find a convenient spot for it on my desk. It was huge and made my keyboard awkward to use. Meanwhile, I can carry my iPad around with me and am not tethered to my desk for digital drawing.
I also have terrible vision, it's far easier for me to read (the internet) on an iPad than on my phone.
How do you feel about convertible laptops, then? That should give you the tablet-like experience you prefer, but it's a full-featured computer instead of a crippled sorta-computer.
I will never buy another laptop that does not become a tablet, whether by turning the hinge all the way around or by pulling the screen off. I prefer the latter design but most of the industry seems to have settled on the former. My favorite laptop I've ever owned from a hardware design perspective was a Thinkpad Helix.
Imagine if it was just like, a slightly thicker device and the screen slid up to reveal a keyboard, how crazy would that be amiright? Hopefully one day we have the technology...