Everyone already has ICQ. Does it glitch? Well, a LOT of people have it, and you can see who's online and who's offline. There's Hamachi for those who are connected to the network.
And finally(!) - there's the tournament website itself. The rules state that you need to notify us if you can't contact your opponent. But you can also use the website itself for communication.
And how about this - we'll add to the rules that installing WhatsApp on a smartphone is mandatory, and that you must also provide your WhatsApp contact (while sharing your mobile number with everyone) during registration? And will that be a 100% guarantee? )))))
Maybe it's better to close this topic?
My opinion is this: if an opponent wants to play, they will get in touch, even with the current conditions.
If not, then even banging on the rails won't help, and no WhatsApp will make a difference.