I’m one to agree with the messy number of people in one group. However, to put the evaluation only on the number of people is rather simplistic, and shallow. Telegram is much helpful in term of enhancing teamwork, since it provides one-stop centre service where people in the group can share documents, links (with thumbnails and quick view!!!), and of course video and pictures (in optional actual size and compressed). Again, it’s not the app that mess up with our lives, it’s how we use it.
p/s-Whatsapp is just bullshit, you can’t even think about other function than pure gross socialising.