Also, they don't fully replace more traditional cooking apparatus, like a pressure cooker, a crock pot, or rice cooker. We have all 4, and what the Instant Pot got a lot of use initially we found that the for purpose cooking pots worked better and got better results. So the Instant Pot slowly fell out of favor.
About the only place the Instant Pot falls down a bit as a pressure cooker is when you need the full 15psi, like the Modernist Cuisine recipe that pressure-cooks squash with a bit of baking soda to kick in the Maillard reaction. The recipe works great in a stovetop pressure cooker that hits 15psi but fails in an Instant pot that only hits around 12.5psi or so - you can always taste the baking soda when it is done cooking. The pressure difference might also impact making stock but I haven't tried a side by side (though the Instant Pot is non-venting so I'd expect it's stock to at least have superiour clarity).
If I could only pick one out of the four, it would be the IP. No question.
I used to have a Cuckoo pressure rice cooker that made the best rice, fast, but it eventually started leaking even after replacing the seals, and professional repair would have been prohibitively expensive in Canada
Or by pressure cooker do you mean a "on the stove double boiler-like" setup?
(1) An electric pot that can be used like a regular stovetop pot,
(2) A pressure cooker, and
(3) A slow cooker (and a few other things that are typically specialized single-use devices but are really slight variations on those 3 things)
More advanced models are also:
(4) immersion circulator (“sous vide" cooker), and
(5) air fryer.
In many of these roles it is often seen as sonewhat less good than a dedicated device, though even people who feel that way may see it as useful as a multitasker and because it can more conveniently do dishes that require more than one function without changing pots.