From long time macOS and iOS developer Panic (the folks who produced the excellent Firewatch game, mentioned yesterday):

If you remember, 2016 was the year we killed Status Board, our very nice data visualization app. Now, a lot of it was our fault. But it was another blow to our heavy investment in pro-level iOS apps a couple years ago, a decision we’re still feeling the ramifications of today as we revert back to a deep focus on macOS. Trying to do macOS quality work on iOS cost us a lot of time for sadly not much payoff. We love iOS, we love our iPhones, and we love our iPads. But we remain convinced that it’s not — yet? — possible to make a living selling pro software on those platforms. Which is a real bummer!

The macOS marketplace is so much smaller than that for iOS, it’s much easier to stand out in the crowd, get the word out on excellent work. In addition, the smaller market allows for higher prices, so you can break even selling fewer copies.