Yes they are, but as an additional measure it looks like they suggest the below, which is what i've been doing as well (probably my "specialism" kicking in.
) It does no harm and certainly will defrost the rubber. I've done it veryday since I picked up last Wednesday as it's been -umpteen since I got it
It takes 10 secs, if that, to do it when you're parked up for the night, so I thought, why not
Wipers
If you expect snow or ice to build up when parked, touch Controls > Service > Wiper Service Mode. This raises wipers against the windshield so they can defrost when the windshield defrosts (see Wipers and Washers). You can also turn on wiper defrosters (if equipped). See Climate Controls.