Maybe that's regional but here in Spain it's very popular for clubs. We use it for our makerspace and also for several other clubs. The moderation and access tools are way better than WhatsApp's.

It's not end to end encrypted but for big group channels that anyone can join that doesn't really matter.

Here it's all WhatsApp and Telegram. iMessage isn't really a thing at all except for expats. Because most locals use smarties. I don't accept sms or rcs either.