The type of trading that you spend more time on desktops, laptops or monitors can make trading very boring. That was the beginning of trading when very fast smart phones were still not out, expensive and far from the reach of newbie traders and traders who were still struggling. But you can see in your post too that with mobile phone, you can check chart, analyse trade , interchange trading pairs and do everything done with desktops including making orders.
Never said you couldn't do these things on your phone; it's just that using it on a proper computer is just going to be more efficient. Even if your phone is as fast as the fastest latest computer, it's simply less efficient solely due to the screen size alone.
And the main goal of trading in the first place(if you're doing it professionally) is to make money, not necessarily to have a great time.