A question about lifting messages

Just for my own edification: why have you used the idea of lifting messages (e.g.``` lift << Mdc```) instead of using ```Html.map``` and ```Cmd.map``` in the Elm file that contains the component?

In ```Material.elm``` you wrote:

> - `Material.Model` and `Material.Msg` have to know your top-level message type
> `Msg` for technical reasons.

Can you give me some insight into those technical reasons? I've followed your practice, and I'd just like to understand the pattern better.