What tracker patch are you referring to? They changed it several times and I hardly doubt there was any massive exodus due to any of them. The loud minority on reddit is not representative of the game's community in large.
When the game experienced the most instability it hadn't even been launched in most countries.
The first one, when they dropped third parties and removed the already-bugged step count under close-by pokémons.
It's purely anecdotic, but after that release, popular spots (with multiple pokestops and arena in one place) usually crowded with more than 50 people playing actively were down to one dude on a bench.
Sure the "loud minority" is not representative of the whole game's community, but they were it's core players. They shaped the game's community (and niantic didn't helped) from the beginning. And it didn't help when those people decided to stop playing.
Back to server's issues, Google CREs did a very good job during these times. They can't be blamed for trying to scale an app that was absolutely not designed to get this high.
There was the patch that broke the tracker. Then there was the patch that "fixed" the tracker by removing the footsteps but basically kept it how it was. This patch was released on July 30th. Around August 23rd, it was reported that Pokemon Go had lost over 10 million users, down from 45 million sometime in July. Here's the article on that: http://arstechnica.com/gaming/2016/08/pokemon-go-sheds-more-...
When the game experienced the most instability it hadn't even been launched in most countries.