Considering that wax molds much better than rubber how would rubber
provide a better seal?

What is better to seat a toilet to the floor, a wax ring (old school)
or the new rubber ring?

From what I read when I was plumbing our house, the wax ring does a better
job with variations in toilet and flange heights. Rubber alternatives work
great if properly sized to your exact gap, but you could have leaks if the
gap is even slightly larger than the rubber ring is designed for.

Old school has worked well for decades, so I chose wax rings for our
toilets. Although, I did use the rings with the plastic "funnels" attached,
to ensure waste goes down the pipe and not around it.

Anthony