This is very often I see on ICO group with members around 50,000 But message/day is only around 20-30, of course this is very suspicious compared to the real telegram group, only about 4000-8000 members are active in the chat. I think this is not entirely wrong from the ICO Team because they usually paid services to individuals or groups but of course it's not professional.
Yes, it is happening now. In real telegram group, they have only 8k to 10K members but every day more than 3 thousands messages come in those groups and almost every message coming from the investor! ICO organizer should know the fake number is nothing to compare with legal members.