> Mobile game display ads seem like a very, very low value business to be in and I would imagine rates are going down all the time
You'd be incorrect. It's a huge business. Less ads in general more paid install services as a result of ads for games, but both are huge businesses tbh.
It's a huge business, but it feels like it's much more of a commodity business.
Changing out the ad network is probably a matter of a fairly simple swap out of highly componentized components. I'm sure devs bounce from network to network fairly quickly chasing better revenue or support experiences.
Changing out a game engine is much heavier plumbing.
From that perspective, Unity might be going for a tail-wags-the-dog approach: making their ad platform stickier by tying it to something sticky, but then you'd expect to see something more direct towards that goal like "we don't allow use of other ad platforms in Unity projects".
They also went for a lot of splash damage on non-mobile scenarios-- ad-supported games don't really exist on the desktop (yes, a modest exception for some casual titles, typically stuff like Facebook-based games)
You'd be incorrect. It's a huge business. Less ads in general more paid install services as a result of ads for games, but both are huge businesses tbh.