I think mainly to make it more malleable from the warming effect. It also makes it more consistent if it has dried around the edges
No. Use the putty.
You can use silicone as a substitute, but plumbers putty is simpler and far easier to clean up. 100% SILICONE
Oils from putty soak into and discolor marble. Putty not used when putting pipe together.
Put putty under outer edge of faucet base and fasten to sink. Remove excess putty after fastening faucet.
Get a candle and use it to heat your putty knife. It will slice though the old putty like butter. Just keep reheating the knife. The best way to soften plumber's putty is to add a little linseed oil and allow it to sit overnight. Knead the putty thoroughly. This won't do if you're in a hurry, so you could try to hurry it along by kneading it with a very small amount of linseed oil (use gloves). Remember to keep the consistency a little bit thicker than Play Doh.
If it is real marble, the oil in the putty can leach into the marble and discolor it.
pipes plunger putty
Search for granite poltice online. For more info go to solidsurfacealliance.org or forum.solidsurfacealliance.org
You can purchase plumbers putty and teflon tape at any local hardware store. These items are also available at large chain home improvement stores such as home depot or lowes.
It will not dry out and if the drain needs to be removed at some point, it can be. Glue would make it difficult to work on. Modern 100% silicone caulk will also work, and can be removed easily, like plumber's putty.
It sounds like you are installing a new faucet. If that is the case read the manufacturer's instructions. If you are re-installing an older faucet, using the plumbers putty doesn't hurt.
One can repair wood grain in a car with epoxy putty. It's a two-part putty that you knead together then fill in the cracks. It doesn't shrink, so all you have to do is sand it smooth once it has hardened. Then paint it to match the simulated wood color.