Mobile games are good as quick time wasters when you're bored and either don't have a console with you or don't have time to play more long winded games, and they're good for the types of people who prefer the simple gameplay or who aren't serious enough about gaming to buy a dedicated game console or a gaming PC.
There are some console-quality games on mobile if you look for them but generally that's not what the platform is focused on, and if you expect that, you're going to be disappointed.
Mobile games have their place, but they're not really for me. I do play them occasionally when I'm not at home and need to waste some time and I don't feel like loading up BotW or Mario Odyssey etc though.
