In my humble opinion: anyone optimizing for "engagement" is trying to make a product inherently addictive.
Having a great product is not, but designing your product intentionally so people spend more time with it, than they wanted - intentionally not just let them write that one message, but distract them into other stuff - would qualify.
Having a great product is not, but designing your product intentionally so people spend more time with it, than they wanted - intentionally not just let them write that one message, but distract them into other stuff - would qualify.