Well yes that is what I was referencing. That is how many people use them; out at restaurants, public places, at friends, etc. Often they are watching TV on them anyway.
But outwith that they have a whole host of problems even when used correctly and little upside. Autoplay, bright colors, fast-paced and visually rich interfaces. Locked in 20cm from the screen. Instead of learning to entertain yourself quietly. Engaging with your other senses.
Exception is well developed education apps for cognitive impairments, developmental delays, etc where the crazy engagement the design envokes can be useful.
Heavier or more awkward than you can comfortably carry. Weekly/monthly food shop, furniture, weekend getaways, etc.