Why tho? I am not old and this is fairly standard in my work place, some forums I use, messages with friends etc. Maybe it’s a culture thing but definitely not an old people thing imo. Its the easiest way to send an acknowledgment or agreement with a message without spamming the group chat and it makes it easier to count if you interpret it as votes.
Edit: I am talking about reacting to the messages directly, I don’t reply to someone with just a thumbs up emoji when I can just say Ok in most context.
That’s cool, could you share some photos? The theramin I mean