why do chess coaches always use Skype, zoom and meet?

no offense but I have a question. Why do chess coaches always use Skype, Zoom and Meet and nothing else? You guys will be like, "Well WhatsApp's not a meeting app." True true. I'm absolutely not talking about WhatsApp. As far as I know, all the coaches use one of these three. But there are many other suitable apps that deserve promotion. Even the very popular Viber, Telegram and Messenger are suitable to have chess lessons. I saw a coach who showed me his number on Viber and I was like oh, I finally escaped those three. I downloaded the app and texted him to enquire. And guess what happened? He sent me his Skype account. Just wondering, what really are so attractive about Skype, Zoom and Meet. if you are a coach, please tell me the logic.

I’ve always use zoom with my coaches and playing partners.

We can share screens and odes everything we need to.

Could be because you are half way around the world, things are different.

Really? It is a great app you should try

Does viber and telegram have features that zoom and Skype don’t have? Zoom and Skype are also larger platforms meaning more people are likely to have those than any other competitor.

I prefer Viber and Telegram if you ask me..they have screen sharing features and are like more user friendly especially for mobile phone users. They can send text messages for some easy communication..

well zoom and skype are just more popular so deal with it i guess

Zoom and Skype also have screen share

I can’t say whether they are more user friendly though since I don’t use mobile. 

I don't do chess coaching, but I do a lot of video calls online and can answer this anyway.

Whatsapp is terrible for video calls, as it doesn't work cross-platform.
I have no idea what Viber is and I doubt I'm the only one.
Telegram requires a phone number in order to use it and it's video meeting system is a bit weird.
Many try to avoid Facebook stuff, either because of tracking issues or because they don't want to mix work and pleasure. This rules out Messenger in most situations.

Google Meet, Skype and Zoom all work cross-platform and are much simpler for people to use. They also include screen sharing, which I think Telegram may be missing (I could be wrong on that though).

Skype is old school and generally not used by techy people, but chess players aren't necessarily that techy, so perhaps that's why.

I looked up Viber just now. It work cross-platform either by the looks of it, so will presumably be why that isn't used.

yeh I have never heard of Viber