Why is the Lift Delivery a Thing?

Watching the Brier this week, and seeing Kevin Koe use a lift delivery, has got me wondering: what was the rationale behind ever doing this in the first place?

I was told at some point that it was because they make it easier to generate heavy weights, but that doesn't really make sense. You can get the rock moving pretty much as fast as you could want with a non-lift delivery, and the 42lb rock isn't going to do much to help accelerate the 100+lb human holding it in any case.

Was the ice or the hacks different somehow in a way that made the lift delivery helpful? Did older rocks or handles have some difference I'm not thinking about?

Obviously there's nothing wrong with lift deliveries--Kevin Koe can be Kevin Koe while using one, so it must be fine--but I just don't see what people ever could've thought the advantage was.