Email with real-time push notifications is not free. Without push notifications, WhatsApp, or any other messaging platform is essentially DOA. Theoretically, we only have Apple and Google with their limited operating systems in the early years to blame for the rise of the notifications economy.

Edit: While there are free email solutions that provide free push, you are either tied to the platform or are made to download an email app, which just makes WhatsApp an easier to use alternative, even if your use case is just spamming groups with pictures or video.

How about group email on demand? Setting up a group takes a few seconds, so does exiting or blocking. Ever imagine doing that with yahoo groups? I have some permanent groups but we have created and dropped so many need based groups. No need to accept the group by logging in here and clicking this and so on.