A new WhatsApp Beta has fleshed out what multi-device support means for the popular messaging app. WhatsApp will soon support up to five devices simultaneously, but not multiple smartphones.
https://www.notebookcheck.net/WhatsApp-multi-device-support-is-not-necessarily-what-it-sounds-like.547256.0.html
is necessary and works very well even with contacts that's not have the same version, so I don't understand what is the point of the article