I have seen people say that phones could replace computers

How?

They have worse browsers, worse games, less customizability, smaller screens, less input options, worse input and display less information

Could someone please explain to me why phones are considered so good?

Edit: even if this new feature solves 4th, 5th and 6th problems, why use that instead of a computer? You are already sacrificing the mobility

I 'member the Atrix lapdock

https://en.wikipedia.org/wiki/Motorola_Atrix_4G