No, granite countertops are highly stain-proof but certainly not 100% stain-proof.
Granite is a dense material and is very stain resistant due to its sealing and polishing process.
Your granite countertops have been treated with a high-density impregnator so that water will bead on the surface and not soak in.
This impregnator lasts for years and is simple to reapply. You should always wipe out oil and grease immediately and not let it sit for hours on end.
Most problems can be prevented by not leaving “leaking” items on countertops for long time.