I'd argue the opposite. For a lot of people, getting quick results is absolutely needed for motivation. Focusing on learning "the fundamentals" before getting to the enjoyable parts is bad advice for most, as it often leads to people dropping out before they get hooked.
I agree that you probably can't be a decent mobile dev in the long term without learning basic iOS/Swift or Android/Java(/probably Kotlin nowadays) but that is not a good place to start for people who are just getting started.
I agree that you probably can't be a decent mobile dev in the long term without learning basic iOS/Swift or Android/Java(/probably Kotlin nowadays) but that is not a good place to start for people who are just getting started.