"string" data type with readln

[pascal111 via Digitalmars-d-learn]

I tried to type small program, and tried to use "string" data 
type with "readln", but the compiler refused it, and I had to use 
"char[]". So, if we can't use "string" with "readln", so what's 
its benefit? why we need to use it?

Code source:
https://github.com/pascal111-fra/D/blob/main/proj01.d