Of course they do, in absence of the 3rd party apps that is how I would still be able to browse without ads on my phone. (If I didn‘t already switch fully to kbin and Lemmy)
I also expect one of these annoying "Disable your adblocker" pop ups for Desktop users.
This post is from early May, so probably long before they decided to kill the API (and the actual experiment could have started long before that post).