Yes, it'll take some time before more users get videos for desktop ads. I have yet to get one ad for that. The incentive looks promising. Hope it becomes more available. 
For mobile ads, not necessarily. It seemed that there was little to no waiting time for earning coins these past few weeks. It's only recently that there's been a lack of access or limit to how many videos you can watch daily. 
Other users have been noticing it too. It helps to share our experience here since others may assume it's only happening to them unless they read about similar experiences from fellow users. 