Left for the same reasons - it was interferring with my photography. Around the same time, other services like Smugmug and Zenfolio got better (I think Smugmug is now a little more up to date than ZF's look, but not originally).
Flickr decided for a long time to not prioritize the best photo display possible and limited photo size and wouldn't offer things like black backgrounds.
And now I may get an infinite less number views, I don't have to deal with the comments, and photography is no longer associated with gamification (when do I post this for the most views to hit explore, etc).
Flickr has a bit of a "look" to what is popular, and while I'm big on good photo processing and the history of the dark room, what makes it today is often too processed, too HDR, and so on, and playing the "game" is not something I'm interested in.
In the early days of Flickr, people DID look more at all the photos in groups they posted to, and that was pretty great.
Getting more people into photography is great though - just shouldn't be about numbers.
