Why is it discouraged to accept a reference to a String (&String), Vec (&Vec), or Box (&Box) as a function argument?

I wrote some Rust code that takes a &String as an argument:

fn awesome_greeting(name: &String) {
    println!("Wow, you are awesome, {}!", name);
}

I’ve also written code that takes in a reference to a Vec or Box:

fn total_price(prices: &Vec<i32>) -> i32 {
    prices.iter().sum()
}

fn is_even(value: &Box<i32>) -> bool {
    **value % 2 == 0
}

However, I received some feedback that doing it like this isn’t a good idea. Why not?