If the friction gets too high you end up with a frozen (seized) spring. Lubrication helps keep the rust at bay and potential seizing also. Don't need to use the spring for damping - they are separate .
Cheers,
Graham (G4FUJ)
Sold L44FOR 4/4 Giallo Fly '11 MINI Countryman Cooper D All4 '90 LR 90 SW