You can; but usually shakes are used for convenience. Protein calories are protein calories so I’d rather eat chicken. But if I’m in a rush or I’m lazy I will grab a shake. Why do you want to meal replace?
I like drinking these for breakfast. That way it keeps me satisfied for most of the day, so I’m not snacking or eating extra calories. I’ve also used it as a creamer in my coffee. It gives the extra protein and some added flavor!