But I am just used to consider "$0" and "$1, $2 ... $n" different/separate things, being "$0" solely a locality sintax.
Well I don't know about implementation, but conceptually, I don't see $0 (in object boxes) as something that much different than $1..$n: you can think of $0 as just one more creation argument of the containing patch (a numeric value), only that it is assigned automatically and guaranteed to be unique.