Amazes me so many people stick to WhatsApp even though it holds one back - There are better instant messenger options!
WhatsApp has never been the most innovative service around. Others went with bigger groups, earlier security features, better stickers and GIFs, and yes WhatsApp stiil won't work by default if you have lost your phone. Let's repeat that: If you lose your phone or your phone's battery is flat or inoperable, by default your web client / browser access for WhatsApp won't work! So you can't leave your friends a message to say you're offline.
Yep you are really better off getting your friends onto messengers like Telegram (does voice calls but not video, and supports massive broadcast groups) or Wire (voice and video calls). Both of these are end-to-end secure messengers that will continue to work from a browser after you lose your phone (you do need to have configured your browser initially though). Wire can be found at https://wire.com and Telegram at https://telegram.org.