People will probably continue downvoting you as long as you continue to complain about downvotes. Downvotes happen, whether randomly or because someone is having a bad day. Making a fuss out of it is counterproductive.
I upvoted you. Last time I tried it, using Whatsapp on your computer requires you to have the phone on. I think this is because the app on the phone holds your private key. I imagine this is also the reason why you can't use your whatsapp on a tablet or on multiple phones.