What's the function of rubber steel gaskets?

There are four functions of rubber steel gaskets,showed as below:

1/ High surface pressures are absorbed by the rigid ‘body’ of the seal.
2/ The flat steel ring (corrosion resistant) easily absorbs pressure from the inside out.
3/ The seal can easily be mounted, because the seal is self-centering.
4/ The sealing shapes itself to the surface of the flange, even with minor damages.