I had one of the older style air fryers around 12 years ago. Those were much smaller and not oven like. I think they were ideal for making small portions and especially good for re-heating food the next day.
These newer ones do seem a bit like a smaller, more efficient oven. Again, I reckon it would be useful for a lot of smaller stuff I use the main oven for, but we just don't have the space in the kitchen for one.