WhatsApp is solving this ‘big’ contacts problem with the new Manage Contacts features

WhatsApp is now going to allow users to add and manage contacts from any device, bringing a major change to its previous mobile-only contact management system. The update, rolling out gradually over the coming weeks, will first be available on WhatsApp Web and Windows platforms before expanding to other linked devices.
The messaging platform is also introducing a new feature allowing users to save contacts exclusively within WhatsApp, rather than to their device’s general contact list.