Also kind of odd because messaging apps use a trivial amount of data unless you're doing video. But most people may not know that and then switch to them for "unlimited" and there you go.

There's this new pattern of communicating where you talk with multi-megabyte reaction gifs back'n'forth instead of writing two or three words. Unlimited data may prove useful in that scenario.

Also exchanging pictures/selfies with the family/friends generates quite a bit of data if you do it on a daily basis.

It is amazing what can be done with 20+ year old technology.

Not that odd: It increases the perceived value of a plan without costing the provider much in traffic.