I have no idea how the block works, but I learned that WhatsApp video calls are blocked in the United Arab Emirates, along with almost every other video chat app. There’s a UAE sponsored app called Totok that works, although it is/was removed from the Apple Store for privacy reasons. Recently they started allowing Zoom calls to go through.

Further reading:

https://www.cnbc.com/2020/03/26/coronavirus-lockdown-uae-res...

It's better to ask why Telegram was blocked, and I think it's often been because of their channels:

https://telegram.org/tour/channels

In this case it's more relevant to ask why Twitter or Facebook haven't been blocked (if they haven't).

I think WA has a similar feature ("broadcast") but not as widely used (since it is limited to 256 people).

WhatsApp broadcasts act a little differently than Telegram channels; they end up as normal messages in a 1-on-1 chat with each recipient (with a megaphone icon next to it), so it's not something you can join or even have as a separate section.

WhatsApp groups can be set to act like channels, however, by changing permissions to allow just group admins to send messages.

This.

Channels are pretty much news feeds of note.

And they scale from a community, through to global classes of people.