Many "Pokemon Go" players around the world are up in arms over developer Niantic Labs' move to ban Pokevision and other third-party Pokemon tracking apps from the game. In a way, it was a form of cheating; not outright, but it circumvented how the game was meant to be played.
However, Niantic explains in a long blog post released on the "Pokemon Go" blog yesterday that they did this for a very good reason: so that they can finally move closer to launching the game in other countries. They described that these third-party apps basically took up too much of "Pokemon Go"'s resources by trying to access the game's already loaded servers, and essentially could become platforms for other, more serious forms of cheating, even though getting an edge in tracking seems totally harmless. A graph they published showed a steep drop in server activity immediately after they blocked all access by the third-party apps.
By doing this, Niantic was able to release "Pokemon Go" in other markets such as Brazil. It's probably safe to note that after this move, territories waiting for the game to arrive on their shores won't have to wait much longer. Even though new third-party tracking apps keep popping up, it's safe to expect Niantic to continue cracking down on them.
As for the actual Nearby Pokemon tracking app in "Pokemon Go," which was removed for simply being broken, Niantic says that they're still working on a fix. It's just that they had to devote time and effort into fixing this other problem, which diverted their resources from developing new features or fixing old ones. We'll have to hang tight for the solution to tracking, but in the meantime, at least the rest of the game works as intended.