You can actually pay for Instagram, if you don't want ads. You still have messages tied with the feed.
Now, one must also say that Instagram wasn't the incumbent messaging platform in any place in the world. It's just that newer generations always cannot tolerate to do things like their parents did, so if their parents primarily used Whatsapp or Facebook Messenger (oh, wait, all of them owned by Meta!) to communicate, they ought to find a new platform to get locked in.