It reflects the lack of content in the article, which boils down to, "things changed so I'm leaving." Lincoln isn't claiming that Quora is doing fine. (At least not in this comment.)

I find it useful to be reminded that as a species mankind hasn't figured out how to grow things without changing them (and so exposing them to the possibility of decline).

I'd like to put that stronger: it's impossible to grow things without changing them.

Change for change sake isn't always good but in this case its understandable why Quora is changing (more users = more $) and it's too early to say that Quora is dying because of the lowering of the average user IQ. If Quora is in danger of becoming a less popular version of Yahoo Answers it need only make some new changes.